ⓘ Collagen, type IV, alpha 3

                                     

ⓘ Collagen, type IV, alpha 3

Collagen alpha-3 chain is a protein that in humans is encoded by the COL4A3 gene.

Of type IV collagen, the main structural component of basal membranes, is a multimeric protein composed of 3 alpha subunits. These subunits are encoded by 6 different genes, alpha 1 through alpha 6, each of which can form a triple helix structure with 2 other units for the formation of type IV collagen. This gene encodes alpha 3. In Goodpastures syndrome, autoantibodies bind with collagen molecules in the basal membrane of alveoli and glomeruli. Epitopes which induce these autoantibodies are localized mainly in the non-collagenous c-terminal domain of the protein. Specific kinase fosfauriliruet amino acids in this same C-terminal region, and expression of this kinase are activated in the pathogenesis. There are several alternative transcripts, which appear to be unique for the human alpha 3 gene and alternate splicing is restricted to the six exons that encode this C-terminal domain. This gene is also associated with autosomal recessive forms of Alport syndrome. Mutations contributing to this syndrome are also found in the exons that encode this C-terminal region. Like other members of the type IV collagen gene family, this gene is organized in a head conformation with another type IV collagen gene so that each gene pair shares a common promoter. Some exons of this gene are interspersed with exons of a gene which is nonspecific to the opposite shore.