Evolution of the silk moth chorion gene superfamily: gene families CA and CB.

The nucleotide sequences of two developmentally early chorion cDNA clones from Bombyx mori define two distinct proline-rich chorion protein families, which we name CA and CB to indicate their homologies to the previously defined chorion protein families A and B, as well as the developmentally late and cysteine-rich HcA and HcB chorion families. Thus, the chorion gene superfamily has two symmetrical branches, each consisting of three families: the alpha branch (A, CA, HcA families) and the beta branch (B, CB, HcB families). The evolution of the superfamily is discussed.