9QJ5 | pdb_00009qj5

Structure of the Complement classical and lectin pathway proconvertase, C4b2

External Resource: Annotation


Protein Family Annotation Pfam Database Homepage

ChainsAccessionNameDescriptionCommentsSource
PF00092von Willebrand factor type A domain (VWA)von Willebrand factor type A domainDomain
PF00084Sushi repeat (SCR repeat) (Sushi)Sushi repeat (SCR repeat)Domain
A,
B [auth C],
C [auth B]		PF21145Complement C4, MG1 domain (C4_MG1)Complement C4, MG1 domainComplement component C4 is a non-enzymatic component of C3 and C5 convertases and essential for the propagation of the classical complement pathway. It covalently binds to immunoglobulins and immune complexes and enhances the solubilization of immune ...Complement component C4 is a non-enzymatic component of C3 and C5 convertases and essential for the propagation of the classical complement pathway. It covalently binds to immunoglobulins and immune complexes and enhances the solubilization of immune aggregates and clearance through CR1 on erythrocytes. C4 is cleaved into the fragments C4a and C4b by MASP-2 protease. C4A isotype is responsible for effective binding to form amide bonds with immune aggregates or antigens, whereas C4B isotype catalyses the transacylation of the thioester carbonyl group to form ester bonds with carbohydrate antigens. This entry represents the macroglobulin 1 (MG1) domain found at the N-terminal of C4 [1].
Domain
A,
B [auth C],
C [auth B]		PF17791Macroglobulin domain MG3 (MG3)Macroglobulin domain MG3This entry corresponds to the MG3 domain found in complement components C3, C4 and C5. Domain
A,
B [auth C],
C [auth B]		PF01835MG2 domain (MG2)MG2 domainThis is the MG2 (macroglobulin) domain of alpha-2-macroglobulin in eukaryotes [1]. Alpha-2-macroglobulins (A2Ms) are plasma proteins that trap and inhibit a broad range of proteases and are major components of the eukaryotic innate immune system. How ...This is the MG2 (macroglobulin) domain of alpha-2-macroglobulin in eukaryotes [1]. Alpha-2-macroglobulins (A2Ms) are plasma proteins that trap and inhibit a broad range of proteases and are major components of the eukaryotic innate immune system. However, A2M-like proteins were identified in pathogenically invasive bacteria and species that colonize higher eukaryotes. This domain is found in eukaryotic and bacterial proteins. In human A2Ms, this domain is termed macroglobulin-like (MG) domain 2 and in Salmonella enterica ser A2Ms, this is domain 4 [2] [3].
Domain
A,
B [auth C],
C [auth B]		PF00207Alpha-2-macroglobulin family (A2M)Alpha-2-macroglobulin family- Family
A,
B [auth C],
C [auth B]		PF01759UNC-6/NTR/C345C module (NTR)UNC-6/NTR/C345C moduleSequence similarity between netrin UNC-6 and C345C complement protein family members, and hence the existence of the UNC-6 module, was first reported in [1]. Subsequently, many additional members of the family were identified on the basis of sequence ...Sequence similarity between netrin UNC-6 and C345C complement protein family members, and hence the existence of the UNC-6 module, was first reported in [1]. Subsequently, many additional members of the family were identified on the basis of sequence similarity between the C-terminal domains of netrins, complement proteins C3, C4, C5, secreted frizzled-related proteins, and type I pro-collagen C-proteinase enhancer proteins (PCOLCEs), which are homologous with the N-terminal domains of tissue inhibitors of metalloproteinases (TIMPs). The TIMPs are classified as a separate family in Pfam (Pfam:PF00965) [2]. This expanded domain family has been named as the NTR module [2].
Domain
A,
B [auth C],
C [auth B]		PF07678A-macroglobulin TED domain (TED_complement)A-macroglobulin TED domain- Repeat
A,
B [auth C],
C [auth B]		PF07677A-macroglobulin receptor binding domain (A2M_recep)A-macroglobulin receptor binding domainThis family includes the receptor binding domain region of the alpha-2-macroglobulin family. Domain
A,
B [auth C],
C [auth B]		PF17789Macroglobulin domain MG4 (MG4)Macroglobulin domain MG4This domain is MG4 found in complement C3 and C5 proteins. Domain
A,
B [auth C],
C [auth B]		PF07703Alpha-2-macroglobulin bait region domain (A2M_BRD)Alpha-2-macroglobulin bait region domainAlpha-2-macroglobulins (A2Ms) are plasma proteins that trap and inhibit a broad range of proteases and are major components of the eukaryotic innate immune system. However, A2M-like proteins were identified in pathogenically invasive bacteria and spe ...Alpha-2-macroglobulins (A2Ms) are plasma proteins that trap and inhibit a broad range of proteases and are major components of the eukaryotic innate immune system. However, A2M-like proteins were identified in pathogenically invasive bacteria and species that colonize higher eukaryotes. This domain is found in eukaryotic and bacterial proteins. In human A2Ms, this domain encompasses macroglobulin-like domain MG5 and 6 including bait region. In Salmonella enterica ser A2Ms, this domain encompasses MG7 and MG8 including the bait region [1] [2]. The Bait region is cleaved by proteases, followed by a large conformational change that blocks the target protease within a cage-like complex. This model of protease entrapment is recognised as the Venus flytrap mechanism [1].
Domain

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

ChainsPolymerMolecular FunctionBiological ProcessCellular Component
Complement C2
A,
B [auth C],
C [auth B]		Complement C4-A

InterPro: Protein Family Classification InterPro Database Homepage

ChainsAccessionNameType
IPR011360Complement B/C2Family
IPR000436Sushi/SCR/CCP domainDomain
IPR018114Serine proteases, trypsin family, histidine active siteActive Site
IPR035976Sushi/SCR/CCP superfamilyHomologous Superfamily
IPR009003Peptidase S1, PA clanHomologous Superfamily
IPR036465von Willebrand factor A-like domain superfamilyHomologous Superfamily
IPR001314Peptidase S1A, chymotrypsin familyFamily
IPR033116Serine proteases, trypsin family, serine active siteActive Site
IPR001254Serine proteases, trypsin domainDomain
IPR002035von Willebrand factor, type ADomain
IPR043504Peptidase S1, PA clan, chymotrypsin-like foldHomologous Superfamily
A,
B [auth C],
C [auth B]		IPR019742Alpha-2-macroglobulin, conserved siteConserved Site
A,
B [auth C],
C [auth B]		IPR009048Alpha-macroglobulin, receptor-bindingDomain
A,
B [auth C],
C [auth B]		IPR041555Macroglobulin domain MG3Domain
A,
B [auth C],
C [auth B]		IPR001599Alpha-2-macroglobulinDomain
A,
B [auth C],
C [auth B]		IPR047565Alpha-macroglobulin-like, thiol-ester bond-forming regionConserved Site
A,
B [auth C],
C [auth B]		IPR018081Anaphylatoxin, complement systemHomologous Superfamily
A,
B [auth C],
C [auth B]		IPR018933Netrin module, non-TIMP typeDomain
A,
B [auth C],
C [auth B]		IPR001840Anaphylatoxin, complement system domainDomain
A,
B [auth C],
C [auth B]		IPR011625Alpha-2-macroglobulin, bait region domainDomain
A,
B [auth C],
C [auth B]		IPR001134Netrin domainDomain
A,
B [auth C],
C [auth B]		IPR008993Tissue inhibitor of metalloproteinases-like, OB-foldHomologous Superfamily
A,
B [auth C],
C [auth B]		IPR011626Alpha-macroglobulin-like, TED domainDomain
A,
B [auth C],
C [auth B]		IPR000020Anaphylatoxin/fibulinDomain
A,
B [auth C],
C [auth B]		IPR036595Alpha-macroglobulin, receptor-binding domain superfamilyHomologous Superfamily
A,
B [auth C],
C [auth B]		IPR002890Macroglobulin domainDomain
A,
B [auth C],
C [auth B]		IPR013783Immunoglobulin-like foldHomologous Superfamily
A,
B [auth C],
C [auth B]		IPR050473Alpha-2-macroglobulin/Complement systemFamily
A,
B [auth C],
C [auth B]		IPR008930Terpenoid cyclases/protein prenyltransferase alpha-alpha toroidHomologous Superfamily
A,
B [auth C],
C [auth B]		IPR048847Complement C4, MG1 domainDomain
A,
B [auth C],
C [auth B]		IPR054587Complement C4A/B, CUB C-terminal domainDomain
A,
B [auth C],
C [auth B]		IPR040839Macroglobulin domain MG4Domain

Pharos: Disease Associations Pharos Homepage Annotation

ChainsDrug Target  Associated Disease
Pharos:  P06681
A,
B [auth C],
C [auth B]		Pharos:  P0C0L4