Wide distribution of the skin type I collagen alpha 3 chain in bony fish.

1. Skin Type I collagens were isolated from the five species of non-teleostean fish and examined with respect to their subunit chains. 2. In addition to alpha 1(I) and alpha 2(I) chains, a fish-specific chain, alpha 3(I), was previously found only in teleostean fish. The present study, however, has revealed the occurrence of alpha 3(I) in a chondrostean fish, white sturgeon. 3. The alpha 3(I) gene appears to have arisen from a duplication of the alpha 1(I) gene near the time of the adaptive radiation of bony fish.