Modulation of testicular galactolipid sulfotransferase activity in vitro by ATP

1989

Biochemical Journal

Evidence is presented for a testicular protein kinase activity capable of stimulating the activity in vitro of a partially purified preparation of the testicular galactolipid sulphotransferase. This enzyme is responsible for the synthesis of the major mammalian testicular glycolipid, sulphogalactosylglycerol, and is an early marker of differentiation during spermatogenesis. This stimulatory activity has been separated by affinity chromatography, using 3',5'-ADP-agarose, from both the detergent-solubilized microsomes (microsomal fractions) and the soluble fraction of the testicular homogenate. The stimulator was eluted from the affinity matrix by either a salt, or, more selectively, a cyclic AMP gradient. Thus this matrix can function as an analogue of 3',5'-cyclic AMP. The activity of the sulphotransferase stimulator was ATP-dependent and coincident with protein kinase activity. Sulphotransferase activity was also stimulated in the presence of commercial preparations of cyclic AMP-dependent protein kinase and stimulation was prevented in the presence of kinase inhibitors. Our results suggest that sulphogalactolipid biosynthesis is regulated by a phosphorylation process during spermatogenesis. In addition, our results suggest that affinity chromatography on 3',5'-ADP-agarose may provide a general method for the purification of cyclic AMP-dependent kinases.

Section: Introductionmentioning

confidence: 62%

Modulation of testicular galactolipid sulphotransferase activity by phosphorylation. Stimulation of enzyme activity in vitro by an endogenous kinase

Sakac

1989

Biochemical Journal

“…"SGG was prepared in vitro from PAP35S by use of the renal galactolipid sulfotransferase (Taylor et al, 1987) since this tissue contains no endogenous SGG (Lingwood et al, 1981), yet GG remains a n effective substrate in vitro (Lingwood, 1985~). "SGC was prepared by using the testicular enzyme for a similar reason.…”

Section: Discussionmentioning

confidence: 99%

“…35SGG and "SGC were prepared in vitro by using adult rat kidney and testicular homogenate from 20 day old rats respectively using GG and GC as substrates together with PAP35S as sulfate donor. The conditions for the renal and testicular galactolipid sulfotransferase reactions were as previously described (Taylor et al, 1987;Lingwood, 1 9 8 5~) .…”

Section: Preparation Of Radiolabelled Sulfoglycolipidsmentioning

confidence: 99%

See 1 more Smart Citation

Male germ cell specific sulfogalactoglycerolipid is recognized and degraded by mycoplasmas associated with male infertility

Journal Cellular Physiology

Schramayr

Quinn

1990

Self Cite

Sulfogalactosylglycerolipid (SGG) is the major mammalian male germ cell glycolipid and has been implicated in sperm/egg binding. Mycoplasma pulmonis, a species of Mollicutes, is associated with male infertility in rodents. Purified SGG incubated in the presence of M. pulmonis was enzymatically degraded by both desulfation and deacylation. Desulfation occurred primarily at alkaline pH, and deacylation also increased with increased pH, indicating that these represent novel enzymatic activities. Digestion was facilitated, but not dependent on, the presence of detergent. Rat spermatozoa exposed to M. pulmonis showed a reduction in SGG content which was particularly marked for cauda (mature) spermatozoa. With the aid of tlc overlay binding procedure, intact M. pulmonis were found to bind specifically to sulfated glycolipids and thus SGG may provide the cell membrane receptor for this organism. The topology of mycoplasma binding to rat sperm was consistent with the known topology of sperm SGG. The reduced binding (and subsequent digestion) of caput spermatozoan SGG correlates with the membrane colocalization of SGG and its endogenous binding protein at this stage. Separation of SGG and its binding protein during epididymal sperm maturation appears to facilitate M. pulmonis binding to and digestion of cauda sperm SGG. The binding and degradation of the sperm SGG by M. pulmonis may play a role in the induction of infertility which follows infection with these organisms by interfering in sperm/egg receptor recognition.

“…der of spermatogenesis (Kornblatt, 1979) and is involved in the mechanism of sperm/egg binding (Tanphaichitr et al, 1992(Tanphaichitr et al, , 1993. The galactolipid sulfotransferase, which has recently been purified (Sakac and Lingwood, 1989), is regulated by a phosphorylation mechanism (Sakac and Lingwood, 1989;Taylor et al, 1987). The enzyme is stimulated early in spermatogenesis by a stimulatory protein kinase and subsequent inhibition of phosphorylation results in reduction in enzyme activity.…”

Section: Introductionmentioning

confidence: 99%

Developmentally regulated testicular galactolipid sulfotransferase inhibitor is a phosphoinositol glycerolipid and insulin‐mimetic

Molecular Reproduction Devel

Sakac

Saltiel³

1994

The synthesis of sulfogalactosylglycerolipid (SGG) is a differentiation marker in spermatogenesis restricted to the zygotene and early pachytene spermatocytes. The galactolipid sulfotransferase responsible for the synthesis of SGG is regulated by a phosphorylation mechanism. The activity of this enzyme is reduced in cells later in spermatogenesis by a low molecular weight inhibitor, which can be extracted in organic solvents and purified by reverse phase high pressure liquid chromatography (HPLC). This purified inhibitor is a potent postreceptor insulin-mimetic, which stimulates adipocyte lipogenesis more effectively than does insulin. Phosphoinositol (PI) glycolipids have been proposed as second messengers of the insulin phosphorylation cascade. These species contain a nonacetylated glucosamine, which renders them liable to cleavage by deamidation. The activity of the sulfotransferase inhibitor was lost following nitrous acid deamidation and was labile to PI specific phospholipase C digestion. Insulin and insulin-like growth factor I were found to inhibit germ cell synthesis of SGG in vitro to some degree but had no direct effect on the testicular galactolipid sulfotransferase assay. These results indicate that the sulfotransferase inhibitor is a glycosyl phosphoinositide similar to the lipid species, which mediate insulin signal transduction and suggest that germ cell SGG biosynthesis may be regulated by a receptor-mediated phosphorylation pathway.