9316140 Maylie-Pfenninger This is a Small Grant for Exploratory Research. The developing acrosome of mouse and guinea pig spermatids contains glycoproteins phosphorylated on complex N-linked oligosaccharides. Preliminary results have ruled out mannose-6-phosphate, as well as several other possible 6-phospho- monosaccharides, as the phosphorylated residue. The nature of the phosphorylated substituent is thus unknown. The phosphorylation itself has been shown to be transient during the transit of the acrosomal proteins to the acrosome, with a half-time of approximately one hour. These and other preliminary results suggest that the phosphorylation is involved in a function important for the biosynthetic pathway of acrosomal glycoproteins, and may be involved in targetting of the proteins to the acrosome. The goal of this project is to identify the specific site on the oligosaccharide which is phosphorylated. This will be done by 1H-NMR analysis of purified phosphorylated oligosaccharides, followed by permethylation analysis. The results will provide novel insights into oligosaccharide biochemistry, and will set the stage for determining the function of this novel phosphorylated sugar. %%% This laboratory has made a novel preliminary finding, that there is an unusual and as-yet unidentified biochemical alteration of proteins destined for incorporation into the acrosomes of mammalian developing sperm. The goal of the project is to use state-of-the- art techniques to identify this biochemical alteration. Such identification is a necessary prerequisite to studying the significance of the alteration with respect to sperm development. This is a "high risk, high reward" pilot study, well suited to the Small Grants for Exploratory Research program. ***
