Bovine lens membrane proteins: MP70, MP64, and MP38 are products of the same gene.

We have carried out limited microsequence analysis of bovine lens intrinsic membrane proteins having molecular weights of 70, 64, and 38 kD. These three polypeptides all have an identical amino acid terminal sequence, at least for the first 17 amino acid residues, indicating a common origin. When calf lens RNA was hybridized with a labeled antisense oligonucleotide common to the amino acid sequence of these three polypeptides, a single message with an apparent molecular size of 2.6 kb was detected. Together, these results indicate that bovine lens MP70, MP64, and MP38 are products of the same gene and that the lower molecular weight polypeptides are the result of degradation (processing) of lens MP70 at its COOH-terminal end.