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96  structures 2673  species 16  interactions 5499  sequences 449  architectures

Family: A2M (PF00207)

Summary: Alpha-2-macroglobulin family

Pfam includes annotations and additional family information from a range of different sources. These sources can be accessed via the tabs below.

This is the Wikipedia entry entitled "Alpha-2-Macroglobulin". More...

Alpha-2-Macroglobulin Edit Wikipedia article

A2M
Available structures
PDB Ortholog search: PDBe RCSB
Identifiers
Aliases A2M, A2MD, CPAMD5, FWP007, S863-7, transcuprein, alpha-2-macroglobulin
External IDs MGI: 2449119 HomoloGene: 37248 GeneCards: A2M
Gene location (Human)
Chromosome 12 (human)
Chr. Chromosome 12 (human)[1]
Chromosome 12 (human)
Genomic location for A2M
Genomic location for A2M
Band 12p13.31 Start 9,067,664 bp[1]
End 9,116,229 bp[1]
Orthologs
Species Human Mouse
Entrez
Ensembl
UniProt
RefSeq (mRNA)

NM_000014
NM_001347423
NM_001347424
NM_001347425

NM_175628

RefSeq (protein)

NP_000005
NP_001334352
NP_001334353
NP_001334354

NP_783327

Location (UCSC) Chr 12: 9.07 – 9.12 Mb Chr 6: 121.64 – 121.68 Mb
PubMed search [3] [4]
Wikidata
View/Edit Human View/Edit Mouse

alpha-2-Macroglobulin (α2M) is a large (720 KDa) plasma protein found in the blood. It is mainly produced by the liver, and also locally synthesized by macrophages, fibroblasts, and adrenocortical cells. In humans it is encoded by the A2M gene.

Alpha 2 macroglobulin acts as an antiprotease and is able to inactivate an enormous variety of proteinases. It functions as an inhibitor of fibrinolysis by inhibiting plasmin and kallikrein. It functions as an inhibitor of coagulation by inhibiting thrombin. Alpha-2-macroglobulin may act as a carrier protein because it also binds to numerous growth factors and cytokines, such as platelet-derived growth factor, basic fibroblast growth factor, TGF-β, insulin, and IL-1β.

No specific deficiency with associated disease has been recognized, and no disease state is attributed to low concentrations of alpha-2-macroglobulin. The concentration of alpha-2-macroglobulin rises 10-fold or more in the nephrotic syndrome when other lower molecular weight proteins are lost in the urine. The loss of alpha-2-macroglobulin into urine is prevented by its large size. The net result is that alpha-2-macroglobulin reaches serum levels equal to or greater than those of albumin in the nephrotic syndrome, which has the effect of maintaining oncotic pressure.

Structure

Human alpha-2-macroglobulin is composed of four identical subunits bound together by -S-S- bonds.[5][6] In addition to tetrameric forms of alpha-2-macroglobulin, dimeric, and more recently monomeric aM protease inhibitors have been identified.[7][8]

Each monomer of human alpha-2-macroglobulin is composed of several functional domains, including macroglobulin domains, a thiol ester-containing domain and a receptor-binding domain.[9] Overall, alpha-2-Macroglobulin is the largest major nonimmunoglobulin protein in human plasma.

Function

The alpha-macroglobulin (aM) family of proteins includes protease inhibitors,[10] typified by the human tetrameric alpha-2-macroglobulin (a2M); they belong to the MEROPS proteinase inhibitor family I39, clan IL. These protease inhibitors share several defining properties, which include (i) the ability to inhibit proteases from all catalytic classes, (ii) the presence of a 'bait region' (aka. a sequence of amino acids in an α2-macroglobulin molecule, or a homologous protein, that contains scissile peptide bonds for those proteinases that it inhibits) and a thiol ester, (iii) a similar protease inhibitory mechanism and (iv) the inactivation of the inhibitory capacity by reaction of the thiol ester with small primary amines. aM protease inhibitors inhibit by steric hindrance.[11] The mechanism involves protease cleavage of the bait region, a segment of the aM that is particularly susceptible to proteolytic cleavage, which initiates a conformational change such that the aM collapses about the protease. In the resulting aM-protease complex, the active site of the protease is sterically shielded, thus substantially decreasing access to protein substrates. Two additional events occur as a consequence of bait region cleavage, namely (i) the h-cysteinyl-g-glutamyl thiol ester becomes highly reactive and (ii) a major conformational change exposes a conserved COOH-terminal receptor binding domain [12] (RBD). RBD exposure allows the aM protease complex to bind to clearance receptors and be removed from circulation.[13] Tetrameric, dimeric, and, more recently, monomeric aM protease inhibitors have been identified.[7][8]

alpha-2-Macroglobulin is able to inactivate an enormous variety of proteinases (including serine-, cysteine-, aspartic- and metalloproteinases). It functions as an inhibitor of fibrinolysis by inhibiting plasmin and kallikrein. It functions as an inhibitor of coagulation by inhibiting thrombin.[14] Alpha-2-macroglobulin has in its structure a 35 amino acid "bait" region. Proteinases binding and cleaving the bait region become bound to α2M. The proteinase-α2M complex is recognised by macrophage receptors and cleared from the system.

Fibrinolysis (simplified). Blue arrows denote stimulation, and red arrows inhibition.

alpha-2-Macroglobulin is known to bind zinc, as well as copper in plasma, even more strongly than albumin, and such it is also known as transcuprein.[15] 10-15% of copper in human plasma is chelated by alpha-2-macroglobulin.[16]

Disease

alpha-2-Macroglobulin levels are increased when the serum albumin levels are low,[17] which is most commonly seen in nephrotic syndrome, a condition wherein the kidneys start to leak out some of the smaller blood proteins. Because of its size, alpha-2-macroglobulin is retained in the bloodstream. Increased production of all proteins means alpha-2-macroglobulin concentration increases. This increase has little adverse effect on the health, but is used as a diagnostic clue. Longstanding chronic renal failure can lead to amyloid by alpha-2-macroglobulin (see main article: amyloid).

A common variant (29.5%) (polymorphism) of alpha-2-macroglobulin leads to increased risk of Alzheimer's disease.[18][19]

alpha-2-Macroglobulin binds to and removes the active forms of the gelatinase (MMP-2 and MMP-9) from the circulation via scavenger receptors on the phagocytes.

References

  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000175899 - Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000030111 - Ensembl, May 2017
  3. ^ "Human PubMed Reference:". 
  4. ^ "Mouse PubMed Reference:". 
  5. ^ Andersen GR, Koch TJ, Dolmer K, Sottrup-Jensen L, Nyborg J (October 1995). "Low resolution X-ray structure of human methylamine-treated alpha 2-macroglobulin". J. Biol. Chem. 270 (42): 25133–41. doi:10.1074/jbc.270.42.25133. PMID 7559647. 
  6. ^ Sottrup-Jensen L, Stepanik TM, Kristensen T, Wierzbicki DM, Jones CM, Lønblad PB, et al. (1984). "Primary structure of human alpha 2-macroglobulin. V. The complete structure.". J Biol Chem. 259 (13): 8318–27. PMID 6203908. 
  7. ^ a b Dodds AW, Law SK (December 1998). "The phylogeny and evolution of the thioester bond-containing proteins C3, C4 and alpha 2-macroglobulin". Immunol. Rev. 166: 15–26. doi:10.1111/j.1600-065X.1998.tb01249.x. PMID 9914899. 
  8. ^ a b Armstrong PB, Quigley JP (1999). "Alpha2-macroglobulin: an evolutionarily conserved arm of the innate immune system". Dev. Comp. Immunol. 23 (4-5): 375–90. doi:10.1016/s0145-305x(99)00018-x. PMID 10426429. 
  9. ^ Doan N, Gettins PG (2007). "Human alpha2-macroglobulin is composed of multiple domains, as predicted by homology with complement component C3". Biochem J. 407 (1): 23–30. doi:10.1042/BJ20070764. PMC 2267405Freely accessible. PMID 17608619. 
  10. ^ Sottrup-Jensen L (July 1989). "Alpha-macroglobulins: structure, shape, and mechanism of proteinase complex formation". J. Biol. Chem. 264 (20): 11539–42. PMID 2473064. 
  11. ^ Enghild JJ, Salvesen G, Thøgersen IB, Pizzo SV (July 1989). "Proteinase binding and inhibition by the monomeric alpha-macroglobulin rat alpha 1-inhibitor-3". J. Biol. Chem. 264 (19): 11428–35. PMID 2472396. 
  12. ^ Enghild JJ, Thøgersen IB, Roche PA, Pizzo SV (February 1989). "A conserved region in alpha-macroglobulins participates in binding to the mammalian alpha-macroglobulin receptor". Biochemistry. 28 (3): 1406–12. doi:10.1021/bi00429a069. PMID 2469470. 
  13. ^ Van Leuven F, Cassiman JJ, Van den Berghe H (December 1986). "Human pregnancy zone protein and alpha 2-macroglobulin. High-affinity binding of complexes to the same receptor on fibroblasts and characterization by monoclonal antibodies". J. Biol. Chem. 261 (35): 16622–5. PMID 2430968. 
  14. ^ de Boer JP, Creasey AA, Chang A, Abbink JJ, Roem D, Eerenberg AJ, Hack CE, Taylor FB (December 1993). "Alpha-2-macroglobulin functions as an inhibitor of fibrinolytic, clotting, and neutrophilic proteinases in sepsis: studies using a baboon model". Infect. Immun. 61 (12): 5035–43. PMC 281280Freely accessible. PMID 7693593. 
  15. ^ Liu, Nanmei; Lo, Louis Shi-li; Askary, S. Hassan; Jones, LaTrice; Kidane, Theodros Z.; Nguyen, Trisha Trang Minh; Goforth, Jeremy; Chu, Yu-Hsiang; Vivas, Esther; Tsai, Monta; Westbrook, Terence; Linder, Maria C. (September 2007). "Transcuprein is a macroglobulin regulated by copper and iron availability". The Journal of Nutritional Biochemistry. 18 (9): 597–608. doi:10.1016/j.jnutbio.2006.11.005. PMC 4286573Freely accessible. 
  16. ^ Liu, Nan-mei; Nguyen, Trang; Kidane, Theodros; Moriya, Mizue; Goforth, Jeremy; Chu, Andy; Linder, Maria (6 March 2006). "Transcupreins are serum copper-transporters of the macroglobulin family, and may be regulated by iron and copper". The FASEB Journal. 20 (4): A553–A554. ISSN 0892-6638. 
  17. ^ Stevenson, FT; Greene, S; Kaysen, GA (January 1998). "Serum alpha 2-macroglobulin and alpha 1-inhibitor 3 concentrations are increased in hypoalbuminemia by post-transcriptional mechanisms". Kidney International. 53 (1): 67–75. doi:10.1046/j.1523-1755.1998.00734.x. PMID 9453001. 
  18. ^ Blacker D, Wilcox MA, Laird NM, Rodes L, Horvath SM, Go RC, Perry R, Watson B, Bassett SS, McInnis MG, Albert MS, Hyman BT, Tanzi RE (August 1998). "Alpha-2 macroglobulin is genetically associated with Alzheimer disease". Nat. Genet. 19 (4): 357–60. doi:10.1038/1243. PMID 9697696. 
  19. ^ Kovacs DM (July 2000). "alpha2-macroglobulin in late-onset Alzheimer's disease". Exp. Gerontol. 35 (4): 473–9. doi:10.1016/S0531-5565(00)00113-3. PMID 10959035. 
  • McPherson & Pincus: Henry's Clinical Diagnosis and Management by Laboratory Methods, 21st ed.
  • Firestein: Kelley's Textbook of Rheumatology, 8th edition.

External links

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

Alpha-2-macroglobulin family Provide feedback

This family includes the C-terminal region of the alpha-2-macroglobulin family.

Literature references

  1. Huang W, Dolmer K, Liao X, Gettins PG; , J Biol Chem 2000;275:1089-1094.: NMR solution structure of the receptor binding domain of human alpha(2)-macroglobulin. PUBMED:10625650 EPMC:10625650

  2. Xiao T, DeCamp DL, Spran SR; , Protein Sci 2000;9:1889-1897.: Structure of a rat alpha 1-macroglobulin receptor-binding domain dimer. PUBMED:11106161 EPMC:11106161

  3. Szakonyi G, Guthridge JM, Li D, Young K, Holers VM, Chen XS; , Science 2001;292:1725-1728.: Structure of complement receptor 2 in complex with its C3d ligand. PUBMED:11387479 EPMC:11387479

  4. Zanotti G, Bassetto A, Battistutta R, Folli C, Arcidiaco P, Stoppini M, Berni R; , Biochim Biophys Acta 2000;1478:232-238.: Structure at 1.44 A resolution of an N-terminally truncated form of the rat serum complement C3d fragment. PUBMED:10825534 EPMC:10825534


Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR001599

This entry contains serum complement C3 and C4 precursors and alpha-macrogrobulins.

The alpha-macroglobulin (aM) family of proteins includes protease inhibitors [PUBMED:2473064], typified by the human tetrameric a2-macroglobulin (a2M); they belong to the MEROPS proteinase inhibitor family I39, clan IL. These protease inhibitors share several defining properties, which include (i) the ability to inhibit proteases from all catalytic classes, (ii) the presence of a 'bait region' and a thiol ester, (iii) a similar protease inhibitory mechanism and (iv) the inactivation of the inhibitory capacity by reaction of the thiol ester with small primary amines. aM protease inhibitors inhibit by steric hindrance [PUBMED:2472396]. The mechanism involves protease cleavage of the bait region, a segment of the aM that is particularly susceptible to proteolytic cleavage, which initiates a conformational change such that the aM collapses about the protease. In the resulting aM-protease complex, the active site of the protease is sterically shielded, thus substantially decreasing access to protein substrates. Two additional events occur as a consequence of bait region cleavage, namely (i) the h-cysteinyl-g-glutamyl thiol ester becomes highly reactive and (ii) a major conformational change exposes a conserved COOH-terminal receptor binding domain [PUBMED:2469470] (RBD). RBD exposure allows the aM protease complex to bind to clearance receptors and be removed from circulation [PUBMED:2430968]. Tetrameric, dimeric, and, more recently, monomeric aM protease inhibitors have been identified [PUBMED:9914899, PUBMED:10426429].

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Pfam Clan

This family is a member of clan E-set (CL0159), which has the following description:

This clan includes a diverse range of domains that have an Ig-like fold and appear to be distantly related to each other. The clan includes: PKD domains, cadherins and several families of bacterial Ig-like domains as well as viral tail fibre proteins. it also includes several Fibronectin type III domain-containing families.

The clan contains the following 218 members:

A2M A2M_BRD A2M_recep Adeno_GP19K AlcCBM31 Alpha-amylase_N Alpha_adaptinC2 Alpha_E2_glycop Arch_flagellin Arylsulfotran_N ASF1_hist_chap ATG19_autophagy BACON Big_1 Big_10 Big_11 Big_2 Big_3 Big_3_2 Big_3_3 Big_3_5 Big_4 Big_5 Big_6 Big_7 Big_8 Big_9 Bile_Hydr_Trans BiPBP_C bMG1 bMG10 bMG3 bMG5 bMG6 BslA BsuPI Cadherin Cadherin-like Cadherin_2 Cadherin_3 Cadherin_4 Cadherin_5 Cadherin_pro CagX Calx-beta Candida_ALS_N CARDB CBM39 CBM_X2 CD45 CelD_N Ceramidse_alk_C CHB_HEX_C CHB_HEX_C_1 ChitinaseA_N ChiW_Ig_like CHU_C Coatamer_beta_C COP-gamma_platf CopC Cyc-maltodext_N Cytomega_US3 DsbC DUF11 DUF1410 DUF1425 DUF1929 DUF2271 DUF3244 DUF3327 DUF3416 DUF3458 DUF3501 DUF3823_C DUF3859 DUF3872 DUF4165 DUF4179 DUF4426 DUF4448 DUF4469 DUF4625 DUF4879 DUF4981 DUF4982 DUF5001 DUF5008 DUF5011 DUF5065 DUF5115 DUF525 DUF5643 DUF916 EB_dh ECD EpoR_lig-bind ERAP1_C EstA_Ig_like Filamin FixG_C Flavi_glycop_C FlgD_ig fn3 Fn3-like fn3_2 fn3_4 fn3_5 fn3_6 FN3_7 Fn3_assoc fn3_PAP GBS_Bsp-like Glucodextran_B Glyco_hydro2_C5 Glyco_hydro_2 Glyco_hydro_61 Gmad2 GMP_PDE_delta GPI-anchored Hanta_G1 He_PIG He_PIG_assoc HECW_N HemeBinding_Shp Hemocyanin_C Herpes_BLLF1 HYR IFNGR1 Ig_GlcNase Ig_mannosidase IL12p40_C Il13Ra_Ig IL17R_fnIII_D1 IL17R_fnIII_D2 IL2RB_N1 IL3Ra_N IL4Ra_N IL6Ra-bind Inhibitor_I42 Inhibitor_I71 Integrin_alpha2 Interfer-bind Invasin_D3 IRK_C IrmA Iron_transport LEA_2 Lep_receptor_Ig LIFR_N Lipase_bact_N LPMO_10 LRR_adjacent LTD Mannosidase_ig MG1 MG2 MG3 MG4 Mo-co_dimer N_BRCA1_IG Na_K-ATPase NEAT Neocarzinostat Neurexophilin NPCBM_assoc PapD_C PBP-Tp47_c Peptidase_C25_C Phlebovirus_G2 PhoD_N PKD PKD_2 PKD_3 Pollen_allerg_1 Pox_vIL-18BP Pur_ac_phosph_N Qn_am_d_aII Qn_am_d_aIII RabGGT_insert Reeler REJ RET_CLD1 RET_CLD3 RET_CLD4 RGI_lyase RHD_dimer Rho_GDI Rib SCAB-Ig SKICH SLAM SoxZ SprB SusE SVA SWM_repeat T2SS-T3SS_pil_N Tafi-CsgC TarS_C1 TcA_RBD TcfC TIG TIG_2 TIG_plexin Tissue_fac Top6b_C Transglut_C Transglut_N TRAP_beta Tuberculin UL16 Velvet WIF Wzt_C Y_Y_Y YBD ZirS_C Zona_pellucida

Alignments

We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets, the UniProtKB sequence database, the NCBI sequence database, and our metagenomics sequence database. More...

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  Seed
(78)
Full
(5499)
Representative proteomes UniProt
(13535)
NCBI
(28420)
Meta
(113)
RP15
(1302)
RP35
(3037)
RP55
(4951)
RP75
(6815)
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  Seed
(78)
Full
(5499)
Representative proteomes UniProt
(13535)
NCBI
(28420)
Meta
(113)
RP15
(1302)
RP35
(3037)
RP55
(4951)
RP75
(6815)
Alignment:
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  Seed
(78)
Full
(5499)
Representative proteomes UniProt
(13535)
NCBI
(28420)
Meta
(113)
RP15
(1302)
RP35
(3037)
RP55
(4951)
RP75
(6815)
Raw Stockholm Download   Download   Download   Download   Download   Download   Download   Download   Download  
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Trees

This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

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Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

Curation View help on the curation process

Seed source: Prosite
Previous IDs: none
Type: Family
Sequence Ontology: SO:0100021
Author: Finn RD , Sammut SJ
Number in seed: 78
Number in full: 5499
Average length of the domain: 89.80 aa
Average identity of full alignment: 23 %
Average coverage of the sequence by the domain: 5.59 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 45638612 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 21.0 21.0
Trusted cut-off 21.0 21.0
Noise cut-off 20.9 20.9
Model length: 92
Family (HMM) version: 22
Download: download the raw HMM for this family

Species distribution

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Archea Archea Eukaryota Eukaryota
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Interactions

There are 16 interactions for this family. More...

Stap_Strp_tox_C CompInhib_SCIN A2M_BRD A2M_recep A2M V-set A2M_BRD MG2 CompInhib_SCIN Sushi MG2 Sushi SSL_OB A2M_recep Trypsin NTR

Structures

For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the A2M domain has been found. There are 96 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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