ɛ‐Crystallin, a novel avian and reptilian eye lens protein

Abstract

Gel filtration of Peking duck eye lens proteins reveals a component eluting just behind δ‐crystallin and comprising approximately 10% of the total soluble protein. The native Mr of this additional component is estimated to be 120000; it appears to be composed of three identical chains of Mr 38000 and pl 7.5. Circular dichroic spectroscopy showed a relatively high α‐helical content. No immunological cross‐reactivity is found with α‐, β‐, γ‐ or δ‐crystallins, and partial amino acid sequence determinations likewise failed to reveal any similarity with other known crystallins. We conclude that this protein represents another and novel family of eye lens proteins, for which we propose the designation ɛ‐crystallin. ɛ‐Crystallin is translated from a 1450‐base mRNA, which has been partially purified. ɛ‐Crystallin is found scattered among avian and reptilian taxa, but not in other vertebrates. Its rate of evolutionary change seems to be as slow as that of α‐ and β‐crystallins. Copyright © 1985, Wiley Blackwell. All rights reserved