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Published on: August 16, 2017
A cysteine-rich protein in the Theromyzon (Annelida: Hirudinea) cocoon membrane
Tarin A Mason1, Patrick J McIlroy, Daniel H Shain
1Biology Department, 315 Penn Street, Rutgers, The State University of New Jersey, Camden, NJ 08102, USA.
Abstract:
The aquatic leech, Theromyzon rude, secretes a flexible, proteinaceous cocoon that is resistant to a broad range of denaturing conditions (e.g. heat, denaturing chemicals). We have partially solubilized the Theromyzon cocoon membrane in 10% acetic acid and identified two major protein fragments. Microsequencing of both Theromyzon cocoon protein (Tcp) fragments generated an identical stretch of the amino-terminal sequence that was used to clone the corresponding gene. The predicted linear amino acid sequence of the resulting cDNA contained an unusually high cysteine content (17.8%). Sequence analysis identified six internal repeats, each comprising 12 ordered Cys residues in a approximately 62 amino acid repeating unit. Sequence comparisons identified homology with undescribed, Cys-rich repeats across animal phyla (i.e. Arthropod, Nematoda).
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