This revised proposal requests five years of support for studies assessing the molecular structure and function of the rat testis galactosyl receptor (RTG-r). Studies of RTG-r protein and mRNA suggest that this receptor is related to the rat hepatic lectin 2/3 (RHL-2/3), the minor species of asiologylcoprotein receptor in the liver. The hepatic receptors are responsible for clearing glycoproteins from the circulation after terminal sialic acid residues are removed.
Five specific aims are presented. 1) Determine the biochemical and molecular structure of RTG-r, including N- terminus amino acid sequence of peptide fragments, carbohydrate analyses, cDNA isolation and sequencing, and mRNA analysis. In addition, a monospecific, affinity-purified antibody will be prepared against purified RTG-r. 2) Determine the site and mechanism of phosphoylationn of RTG-r. 3) Study the functional role of RTG-r in cell-cell recognition in fetal testis and during spermatogenesis. These experiments will assess the role of RTG-r in specific binding between spermatogenic and Sertoli cells and in mediating the potential migration of fetal germ cells on galactose gradients. 4) Determine whether RTG-r in Sertoli cells occupies a preferential surface domain and is responsible for the receptor-mediated endocytosis of specific ligands. 5) Determine whether RHL-1 (major rat hepatic lectin) affects RTG-r function by introducing functional DNA into Sertoli and spermatogenic cells.
| Rivkin, E; Tres, L L; Kaplan-Kraicer, R et al. (2000) Molecular cloning of rat sperm galactosyl receptor, a C-type lectin with in vitro egg binding activity. Mol Reprod Dev 56:401-11 |
| Kierszenbaum, A L; Rivkin, E; Chang, P L et al. (2000) Galactosyl receptor, a cell surface C-type lectin of normal and tumoral prostate epithelial cells with binding affinity to endothelial cells. Prostate 43:175-83 |
| Goluboff, E T; Mertz, J R; Tres, L L et al. (1995) Galactosyl receptor in human testis and sperm is antigenically related to the minor C-type (Ca(2+)-dependent) lectin variant of human and rat liver. Mol Reprod Dev 40:460-6 |
| Mertz, J R; Banda, P W; Kierszenbaum, A L (1995) Rat sperm galactosyl receptor: purification and identification by polyclonal antibodies raised against multiple antigen peptides. Mol Reprod Dev 41:374-83 |
| Kierszenbaum, A L (1994) Mammalian spermatogenesis in vivo and in vitro: a partnership of spermatogenic and somatic cell lineages. Endocr Rev 15:116-34 |
