The Acrosome Stabilizing Factor is a glycoprotein synthesized by the corpus epididymis. This glycoprotein functions to stabilize the sperm from undergoing an acrosome reaction and is a reversible decapacitation factor. In addition to its known biological activity, it has been biochemically well characterized. ASF has a molecular weight of 260,000 daltons and contains two pairs of identical subunits. The subunits have molecular weights of 92,000 and 38,000 daltons. Its amino acid and carbohydrate composition are characteristic of a globular glycoprotein, which is high in cysteine content and is 8.3% carbohydrate by weight. This carbohydrate composition is suggestive of the presence of both high mannose and complex N-linked oligosaccharides with the unusual feature of apprecible amounts of glucose. The well established characteristics of the molecule along with a battery of monoclonal antibodies directed against ASF make it an excellent probe to evaluate function of the epididymis in providing the envbironment for sperm matruation and storage. This proposal will: 1) Utilize pulse labeling and subcellular fractionation of corpus epididymis along with electron microscopic immunocytochemical localization to establish subcellular pathways and molecular modifications during synthesis, transport, and secretion. 2) Evaluate the hormonal control of these processes evaluating both androgens and other partential of hormonal stimuli. 3) The rates and stimuli of secretion of ASF will be evaluated in vitro with organ culture of the corpus epididymis. 4) Previous work has established that the large subunit of ASF decreases in size by 2 to 4 kd after secretion. The temporal relationship of this modification with apparent increase binding of ASF to sperm may suggest that the study of this modification may provide insight into ASF sperm association. Modification of ASF by the liminal environment will be evaluated both chemically for the change in ASF structure and biologically for its ability to reversibly decapacitate sperm. It is envisioned that these studies may provide the insight required to approach the development of new contraceptive technology, new methods to circumvent some cases of infertility.
| Reynolds, A B; Thomas, T S; Wilson, W L et al. (1989) Concentration of acrosome stabilizing factor (ASF) in rabbit epididymal fluid and species specificity of anti-ASF antibodies. Biol Reprod 40:673-80 |
