Sequence comparison of γ‐crystallins from the reptilian and other vertebrate species

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Abstract
Lens crystalline were isolated from homogenates of reptilian eye lenses (Caiman crocodylus apaporiensis) by gel‐permeation chromatography and characterized by gel electrophoresis, and amino acid and N‐terminal sequence analyses. Four fractions corresponding to α‐, δ/ε/β/‐, β‐ and γ‐crystallins were identified on the basis of their electrophoretic patterns as revealed by SDS gel electrophoresis. Comparison of the amino acid contents of reptilian crystallins with those of mammals suggests that each orthologous class of crystallins from the evolutionarily distant species still exhibits similarity in their amino acid compositions and probably sequence homology as well. All fractions except that of γ‐crystallin were found to be N‐terminally blocked. N‐terminal sequence analysis of the purified γ‐crystallin subfractions showed extensive homology between the reptilian γ‐crystallin polypeptides themselves and also those from other vertebrate species, suggesting the existence of a multigene family and their close relatedness to γ‐crystallins of other vertebrates.