Ecto-cyclic AMP-receptor in goat epididymal intact spermatozoa and its change in activity during forward motility
✍ Scribed by Chinmoy S. Dey; Gopal C. Majumder
- Book ID
- 102880217
- Publisher
- John Wiley and Sons
- Year
- 1987
- Tongue
- English
- Weight
- 592 KB
- Volume
- 35
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
Goat epididymal intact spermatozoa have been shown to possess on the external surface specific receptors that bind with high affinity to exogenous [8-3H]cyclic AMP. The ecto-cyclic AMP-receptor activity was not due to contamination of broken or ''leaky'' cells, if any. The binding reaction of [3H]cyclic AMP with the receptors was extremely rapid. Uptake of the labeled cyclic AMP to the sperm cytosolic fraction was undetectable. There was little leakage of cyclic AMPreceptors from intact spermatozoa during the binding assays. The binding reaction was proportional to cell concentration, specific and saturable at 250 nh4 cyclic AMP. The binding of the labelled cyclic nucleotide was nearly completely displaced at saturating concentrations (2.5 pM) of the unlabelled nucleotide. The ecto-receptors showed high specificity for binding to cyclic AMP. The & of the binding sites was approximately 1.7 X lo-* M. The binding interaction was highly sensitive to treatment with proteolytic enzymes: trypsin, chymotrypsin, or pronase (125 pglml). Sonication caused a nearly 450% increase of the ectoreceptor activity. The specific activity of the ecto-cyclic AMP-receptor was approximately twofold higher in the vigorously forwardly motile spermatozoa than in the "composite" cells, suggesting that the ecto-receptors may have a role in modulating flagellar motility.