Author/Editor     Lenasi, Helena; Šlajpah, Maja; Sterle, Maksimiljan; Hudnik-Plevnik, Tamara; Breskvar, Katja
Title     Characterization of plasma membrane fraction from filamentous fungus Rhizopus nigricans
Type     članek
Source     Pflugers Arch
Vol. and No.     Letnik 439, št. 3 Suppl
Publication year     2000
Volume     str. R137-8
Language     eng
Abstract     In the filamentous fungus Rhizopu.s nigricans a steroid hydroxylating multienzyme system is inducible by progesterone and by several other steroids. The biological signal carried by progesterone might be mediated by receptors, located either in the plasma membrane or inside the cell. To elucidate the first possibility, plasma membrane fraction was examined for the presence of progesterone receptors. The isolation of plasma membrane from fungal homogenate containing different other membranes is difficult because of the rigid cell wall. Three different membrane fractions were prepared by differential centrifugation of the fungal homogenate and characterized by plasma membrane and mitochondrial membrane marker enzymes, H+ -ATPase and mit-ATPase, respectively. The same fractions were examined for the presence of specific progesterone-binding molecules. Two of these fractions comprising the highest level of plasma membrane enzyme activity contained also the highest level of specific progesterone-binding compounds: 27,6 fmol/mg protein and 18,8 fmol/mg protein. The correlation between plasma membrane marker enzyme activity and the amount of progesterone-binding proteins in plasma membrane fraction of Rhizopus nigricans might indicate the involvement of these molecules in the induction process.
Descriptors     RHIZOPUS
CELL MEMBRANE
RECEPTORS, PROGESTERONE
ADENOSINETRIPHOSPHATASE
MICROSCOPY, ELECTRON