COL1A2 (Hsap) collagen alpha-2(I) chain alpha-2 type I collagen EDSARTH2 EDSCV epididymis secretory sperm binding protein collagen, type I, alpha 2 type I procollagen alpha 2(I)-collagen OI4 alpha 2(I) procollagen collagen I, alpha-2 polypeptide collagen of skin, tendon and bone, alpha-2 chain alpha 2 type I procollagen gene