ABSTRACT
Three new recombinant cDNA clones coding for gamma-crystallins have been identified in the frog (Rana temporaria) clonotheque by hybrid-selected translation/immunoprecipitation experiments, in addition to the gamma-1-crystallin clone that was isolated and sequenced previously [ Tomarev et al., Gene 17 (1982) 131-138; FEBS Letters 146 (1982) 315-318]. mRNA species coding for all these gamma-crystallins are about 650 nucleotides in length, but differ in structure, as follows from restriction and sequence analysis of the cloned cDNAs. The conclusion is that the R. temporaria genome contains a family of at least four similar but not identical gamma-crystallin genes. The complete nucleotide sequence has been determined for the cDNA of one of these clones coding for gamma-2-crystallin. It is 69% homologous with that of R. temporaria gamma-1-crystallin and contains four regions of partial internal homology corresponding to the four structural folding units of the gamma-crystallin molecules. An unusual feature of the gamma-2-crystallin amino acid sequence is the high lysine/arginine ratio equal to 1.1, in contrast to 0.05-0.16 for other known gamma-crystallins.
