Localization of sulfated glycoprotein-2 (clusterin) on spermatozoa and in the reproductive tract of the male rat
Sulfated glycoprotein-2 (SGP-2) is one of the major proteins secreted by rat Sertoli cells and epididymal cells in culture. The disulfide-linked dimeric protein secreted by Sertoli cells and found in seminiferous tubule fluid is composed of monomers of Mr 47 000 and 34 000 whereas the epididymal pro...
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Published in | Biology of reproduction Vol. 45; no. 1; pp. 195 - 207 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
Society for the Study of Reproduction
01.07.1991
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Subjects | |
Online Access | Get full text |
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Summary: | Sulfated glycoprotein-2 (SGP-2) is one of the major proteins secreted by rat Sertoli cells and epididymal cells in culture.
The disulfide-linked dimeric protein secreted by Sertoli cells and found in seminiferous tubule fluid is composed of monomers
of Mr 47 000 and 34 000 whereas the epididymal protein exhibits monomers of Mr 40 000 and 29 000. When both forms were chemically
or enzymatically deglycosylated, they yielded proteins of similar molecular weight. No modification of the higher molecular
weight testicular form by epididymal cells or fluids could be detected in incubation media. SGP-2 mRNA was localized in epididymal
epithelium by in situ hybridization. Northern blot analysis indicated the testicular and epididymal mRNAs were of similar
size. These findings suggest that the two forms of the protein occur because of tissue-specific post-translational modifications.
The detergent-extracted protein from washed testicular spermatozoa is of the higher molecular weight form while epididymal
sperm carry the lower molecular weight form. Immunohistochemical evidence suggests that the testicular form is removed prior
to the initial segment of the epididymis and the epididymal form is applied in the proximal caput epididymidis. SGP-2 was
immunolocalized to the sperm membrane at the ultrastructural level and was distinctly different from the immunolocalization
of outer dense fiber proteins and fibrous sheath proteins. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0006-3363 1529-7268 |
DOI: | 10.1095/biolreprod45.1.195 |