Avtor/Urednik		Šlajpah, Maja
Naslov		Progesteronski receptorji in heterotrimerni G-proteini v plazemski membrani glive Rhizopus nigricans
Prevedeni naslov		Progesteron receptors and heterotrimeric G-proteins in the plasma membrane of fungus Rhizopus nigricans
Tip		monografija
Kraj izdaje		Ljubljana
Založnik		Medicinska fakulteta
Leto izdaje		2000
Obseg		str. 64
Jezik		slo
Abstrakt		In filamentous fungus Rhizopus nigricans a steroid hydroxylating multienzyme system is inducible by progesterone and several other steroids. The biological signal carried by progesterone might be mediated by receptors, located either in the plasma membrane and/or inside the cell. To elucidate the possibility that progesterone receptors are present in the plasma membrane, we prepared different membrane fraction (14K, 12K, 40K) by mechanical disruption of mycelia and differential centrifugation. The activities of specific mitochondrial and plasma membrane marker enzymes were measured in these fractions. Fraction 40K contained the highest amount of plasma membrane. The protoplast preparation was not succesfull, because of the rigid cell wall. In plasma membrane fraction (40K) the progesterone binding molecules with Kd= 7x10-8 M and Bmax = 325 fmol/mg were determined by saturation binding analysis. In the 40K fraction the highest basal GTPase activity was detected. The GTPase activity was increased by progesterone in dose response manner. Affnity of progesterone membrane receptors for progesterone and therefore provide an evidence for membrane bound progesterone receptors coupled to G-proteins. The results obtained with pertussis toxin treated fungal mycelia suggest that progesterone binding molecules in plasma membrane of Rhizopus nigricans are not coupled to Gi/Go proteins, but rather to Gs like proteins.
Deskriptorji		RHIZOPUS RECEPTORS, PROGESTERONE CELL MEMBRANE G-PROTEINS