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Updated: Aug 11, 2026

Phosphopeptide Analysis of Rodent Epididymal Spermatozoa
Published on: December 30, 2014
Characterization of high-affinity protein D binding sites on the surface of rat epididymal spermatozoa
1Department of Biochemistry, North Carolina State University, Raleigh 27695-7622, USA.
Abstract:
125I-labeled protein D was shown to bind to whole rat epididymal sperm in a time-dependent, saturable, and reversible manner. Scatchard analysis indicates that there are 3.4 x 10(5) binding sites/sperm cell with a binding efficiency (Kd) of 2.3 x 10(-10) M. Binding of protein D to sperm reaches equilibrium by 95 min. and is reversible by 30 min. Specific binding of protein D to sperm pre-treated with a dilute trypsin solution is reduced significantly when compared with controls. Our findings establish that protein D-specific binding proteins displaying characteristics of a true receptor are present on the surface of rat epididymal sperm.
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