Guanine nucleotide-binding protein regulation of microsomal phospholipase D activity of canine cerebral cortex
| Autor: | Padala V. Reddy, Zhuo Qian, Lester R. Drewes |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
G protein
Guanine Detergents Guanosine Phospholipase Pertussis toxin Biochemistry Cellular and Molecular Neuroscience chemistry.chemical_compound Fluorides Dogs GTP-Binding Proteins Phosphatidylcholine Microsomes Phospholipase D Phospholipase D activity Animals Toxins Biological Cerebral Cortex Ions Molecular biology Guanine Nucleotides Enzyme Activation chemistry Metals Phospholipases Aluminum |
| Zdroj: | Journal of neurochemistry. 54(5) |
| ISSN: | 0022-3042 |
| Popis: | The hydrolytic activity of microsomal phospholipase D from canine cerebral cortex was measured by a radiochemical assay using 1,2-dipalmitoyl-sn-glycerol-3-phosphoryl[3H]choline and 1-palmitoyl-2-[9,10(n)-3H]palmitoyl-sn-glycerol-3-phosphorylcholine as the exogenous substrates. Of several detergents tested, Triton X-100 was found to be the most effective in allowing expression of phospholipase D hydrolytic activity. The microsomal phospholipase D does not require any metal ion for its hydrolytic activity. Calcium and magnesium were slightly inhibitory between concentrations of 1 and 4 mM, but zinc was greatly inhibitory, causing a loss of greater than 90% activity at the 4 mM concentration. Non-hydrolyzable guanine nucleotide analogues such as guanosine 5'-(3-O-thio)triphosphate and guanyl-5'-yl-(beta, gamma-methylene)diphosphonate but not guanosine 5'-(2-thio)diphosphate were able persistently to stimulate phospholipase D hydrolytic activity at micromolar concentrations. Guanosine 5'-(2-thio)diphosphate was capable of partially blocking guanosine 5'-(3-O-thio)triphosphate stimulation of phospholipase D. Aluminum fluoride was able to cause a two- to threefold increase in hydrolytic activity of the phospholipase D. Cholera toxin had a stimulatory effect on the hydrolytic activity of phospholipase D, whereas islet-activating protein pertussis toxin had no effect. These results indicate that regulation of microsomal phosphatidylcholine phospholipase D activity by the guanine nucleotide-binding protein(s) in canine cerebral cortex may play an important role in signal transduction processes as well as in brain choline metabolism. |
| Databáze: | OpenAIRE |
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