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Drosophila Vitelline Membrane Assembly: A Critical Role For An Evolutionarily Conserved Cysteine In The “Vm Domain” Of Sv23, T. Wu, Anita L. Manogaran, J. M. Beauchamp, Gail L. Waring

Biological Sciences Faculty Research and Publications

The vitelline membrane (VM), the oocyte proximal layer of the Drosophila eggshell, contains four major proteins (VMPs) that possess a highly conserved “VM domain” which includes three precisely spaced, evolutionarily conserved, cysteines (CX⁷CX⁸C). Focusing on sV23, this study showed that the three cysteines are not functionally equivalent. While substitution mutations at the first (C123S) or third (C140S) cysteines were tolerated, females with a substitution at the second position (C131S) were sterile. Fractionation studies showed that sV23 incorporates into a large disulfide linked network well after its secretion ceases, suggesting that post-depositional mechanisms are in place to …