Guanylyl cyclase activity in rat brain myelin and white matter.
Purified myelin from rat brainstem was found to have an appreciable level of guanylyl cyclase activity, as seen in the formation of 3',5'-cyclic GMP from [3H]GTP at a rate approximately 45% that of whole brainstem. Freshly isolated myelin from pooled rat brainstems was incubated with GTP in an appropriate mixture. This gave rise to 29.9 +/- 3.6 pmol of 3',5'-cyclic GMP/mg of protein/min measured by HPLC and a similar result (26.7 +/- 2.6 pmol/mg/min) with 125I-3',5'-cyclic GMP radioimmunoassay. The latter method applied to the reaction product from whole brainstem gave a value of 56.6 +/- 3.4 pmol/mg/min. In analyzing brainstem products by HPLC we observed in most trials concurrent formation of a second radiolabeled product that comigrated with 2',3'-cyclic GMP but that, on further examination, proved not to be that product. Its identity remains unknown.
Chakraborty
G
G
Department of Neurosciences, UMDNJ-New Jersey Medical School, Newark 07103.
Ledeen
R W
RW
D000818:Animals; D001933:Brain Stem / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid; D000242:Cyclic AMP / Q000032:analysis; D006150:Guanine Nucleotides / Q000302:isolation & purification / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006162:Guanylate Cyclase / Q000378:metabolism*; D008297:Male; D009186:Myelin Sheath / Q000201:enzymology*; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D014316:Tritium
D006150:Guanine Nucleotides; D014316:Tritium; D006160:Guanosine Triphosphate; D000242:Cyclic AMP; D006162:Guanylate Cyclase