Identification and relatve amounts of crystallin polypeptides in rat, bovine, human and chick lenses

Purpose. The purposes of the près 3nt investigation were to. 1 ) Identify the major crystallin polypeptides in ra:, bovine, human and chick lenses, 2) Compare the relative amounts of these crystallin polypeptides among the four species. Methods. Crystallins frorr young rat (12-14 days), bovine (fetal), human (newborn) and chick (14 das embryo) lenses were identified by oneand two-dimensional electrophoresis, direct Edman sequencing of separated polypeptides, sequencing of tryptic ragments, and comparison to published sequences. Polypeptide spots were quantified by image analysis of twodimensional gels. Results. The majo' crystallin subunits in young lenses from four animal species were identified under our electrophoretic conditions. Interesting differences in the relative amounts of certain polypeptides were also observed. For example, βB2 polypeptide concentrations were high in human, intermediate in bovine and very low in rat lenses. Also, βA2 was found in bovine but not in human or rat. Conclusion. Differences in the pattern of crystallin polypeptides exist in lenses from animal species. Such differences may influence development of opacity. For example, relatively high concentrations of heat stable βB2 found in human lenses may allow longer term protection against crystallin insolubilization compared to young rat lens containing very little bB2. Young ret lens is very susceptible to a variety of cataracts.