Characteristics of α-crystallin related to fiber cell development in calf eye lenses

Abstract

α-Crystallin was isolated from extracts of the epithelium, from seven successive concentric layers of the cortex and the nucleus of calf lenses. In this order the α-crystallin content of the extracts decreased strongly whereas a very high-molecular component with α-crystallin like subunit composition became more and more prominent. Polyacrylamide gel electrophoresis in 6 M urea revealed significant changes in polypeptide composition. In the epithelial cells only trace amounts of the α A 1 and no α B 1 polypeptides were present. The latter ones appeared at a relative late stage of fiber cell development. The sedimentation coefficients of the α-crystallin preparations obtained from the successive lens layers were also determined. Going from epithelium to nucleus the values obtained ranged from 17 to 21 S and passed through a minimum. A clear cut relationship between the polypeptide chain composition and sedimentation coefficient could not be found.