Collagen Type XXI (COL21)

COL21A1 belongs to the family of fibril-associated collagens with an interrupted triple helix (FACIT collagens). FACIT collagens bind to the surface of collagen fibrils and link them with other matrix molecules.Chou and Li (2002) found that serum withdrawal nearly abolished expression of COL21A1 by cultured human aortic smooth muscle cells. Exposure of these cells to PDGF-BB in the presence of serum increased COL21A1 mRNA expression.Fitzgerald and Bateman (2001) determined that the COL21A1 gene contains 30 exons and spans about 190 kb. Chou and Li (2002) determined that the COL21A1 gene spans 337 kb and contains 31 exons, including 2 alternatively spliced first exons, 1 and 1a. No TATAA or CCAAT boxes are present in the 5-prime noncoding regions upstream of exons 1 and 1a.