Immunoblotting and immunofluorescence studies have also identified antigenic changes in acrosomal proteins of guinea pig and mouse late spermatids and spermatozoa consistent with intra-acrosomal protein processing. We have been unable to demonstrate any carbohydrates associated with AM22 or AM29 by lectin staining of Western blots (unpublished data), so the specific nature of potential posttranslational modifications occurring during the late stages of spermiogenesis needs identification. buy asthma inhalers
Tag: Hamster
The protease(s) responsible for the intra-acrosomal size processing of the 40-kDa polypeptide in the hamster or of the SPlO-related proteins in other species are unidentified. In the hamster, the size processing results in two major polypeptides, AM22 and AM29, as well as a set of minor related bands; however, in other species such as the human, baboon, mouse, and bovine, the processing results in a family of several polypeptides but does not appear to result in the production of two major forms . The functional significance of these multiple polypeptide forms is unclear.
Although the mature AM22 and AM29 polypeptides are assembled into a Triton X-100-insoluble acrosomal matrix assembly in epididymal spermatozoa, the 40-kDa putative precursor protein of the round spermatids is readily soluble in Triton X-100. It is possible that size processing of the precursor polypeptide is required for the assembly of the insoluble matrix elements, and this is under current investigation. It is also possible that processing of the precursor protein is required for the binding of the matrix to the outer acrosomal membrane; this possibility, too, is under investigation. flovent inhaler
The human SP10 proteins have been demonstrated to associate with the outer and inner acrosomal membranes of the anterior acrosome and are also present within the equatorial segment . In the mouse, the SPlO-related polypeptides localize to the acrosome by immunofluorescence , but their incorporation into a stable acrosomal matrix assembly was not demonstrated. Our data on hamster spermatozoa demonstrate a more restricted intra-acro-somal distribution and membrane association of AM22 and AM29. These acrosomal proteins are not present in the equatorial segment, and they are associated with the outer acrosomal membrane of the apical and principal segments but not with the inner acrosomal membrane. We have noted an identical distribution pattern of related proteins in bovine spermatozoa , suggesting that this may represent the general acrosomal distribution pattern of SPlO-related proteins in nonhuman spermatozoa. buy ortho tri-cyclen online
The outer acrosomal membrane of hamster spermatozoa adheres to a stable acrosomal matrix assembly composed of two contiguous but structurally distinct elements . This matrix complex binds proacrosin and N-ace-tylglucosaminidase , and possibly other hydrolases, and it remains intact and associated with the hybrid membrane complex after the acrosome reaction . In the present study, we addressed the composition and assembly of these structurally distinct, outer acrosomal membrane-associated matrix elements. buy ortho tri-cyclen
Immunoblotting was performed on Triton X-100-soluble and -insoluble fractions of round spermatids using both polyclonal anti-AM22 and monoclonal anti-AM29/22 (Fig. 11). The Triton Х-100-soluble fraction possessed a polypeptide of 40 kDa that reacted with polyclonal anti-AM22 (Fig. 11, lane 2) and no immunoreactive polypeptide was found in the pellet fraction (Fig. 11, lane 3). In addition, no AM22 or AM29 were noted in these fractions. cialis professional
Parallel immunoblots stained with monoclonal anti-AM29/22 exhibited no immunoreactive bands in either the supernatant or pellet fractions (Fig. 11, lanes 5 and 6). These data suggest that the 40-kDa polypeptide of round spermatids represents a precursor that is processed during late spermio-genesis into mature AM29 and AM22. Since the monoclonal anti-AM29/22 interacts only with the fully mature acrosomal matrix polypeptides and not the precursor form, this suggests that other posttranslational modifications, in addition to size modification, may occur during processing of the acrosomal matrix precursor polypeptide. …Read the rest of this article
AM22/AM29 Expression during Spermatogenesis
Light and electron microscopic immunolabeling was employed to define the temporal expression and localization of the acrosomal matrix polypeptides in spermatogenic cells. When polyclonal anti-AM22 was used, protein expression was noted in the acrosome at all stages of spermatid development (Fig. 9, A, B, D, and E). In late matu-ration-phase spermatids, the staining with anti-AM22 became restricted to the apical and principal segments of the acrosome whereas the equatorial segment was negative (long arrows on Fig. 9, D and E). When monoclonal anti-AM29/22 was used, the acrosome of late maturation-stage spermatids exhibited intense fluorescence staining (long arrows Fig. 9, С and F); however, the acrosome of earlier spermatids was negative (Fig. 9, С and F). Ultra-structural immunolabeling using anti-AM22 demonstrated labeling throughout the matrix of the acrosomal vesicle of round spermatids (Fig. 10). These data indicate that AM29 and/or AM22, or alternatively a precursor protein, is expressed in early spermatids. Moreover, the data suggest that an intra-acrosomal posttranslational protein-processing event, occurring in late maturation-phase spermatids, is required for antigen recognition by monoclonal anti-AM29/ 22. buy diabetes drugs
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