Heterogeneity of .delta.-crystallins of the embryonic mallard lens. Correlation between subunit compositions and isoelectric points

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Abstract
.delta.-Crystallins from the lenses of embryonic mallards (Anas platyrhynchos) were analyzed with respect to native and subunit MW, subunit composition and isoelectric point. Sodium dodecyl sulfate-urea-polyacrylamide gel electrophoresis showed that unfractionated mallard .delta.-crystallins are composed of approximately equal amounts of subunits with MW near 47,000 and 48,000. Agarose gel chromatography showed that the embryonic mallard .delta.-crystallins have native MW slightly < 200,000. Embryonic mallard .delta.-crystallins appear to be tetramers. Five major and 9 minor .delta.-crystallins were resolved by isoelectric focusing. The 5 predominant .delta.-crystallins each cross-reacted with antichick .delta.-crystallin antiserum, and each had a different proportion of the larger and smaller subunits, indciating a direct relationship between the isoelectric point and the subunit composition. The presence of numerous, minor species of native .delta.-crystallins with different isoelectric points suggested that the subunits possess charge and size heterogeneity.