An Mn2+-stimulated neutral-sphingomyelinase in seminiferous tubules of immature Wistar rats.
Mammalian sphingomyelinases have been implicated in many important physiological and pathophysiological processes. The seminiferous tubules of immature (19 day-old) Wistar rats have at least three types of sphingomyelinases, a lysosomal one and two microsomal ones. One of the microsomal sphingomyelinases is active at pH 6.5 and is stimulated by Mn2+ > Co2+ > Mg2+, and the other is active at pH 7.4 and is stimulated by Mn2+ > Mg2+ and inhibited by Co2+. The two microsomal enzymes are only slightly inhibited by EDTA and at pH 7.4 the stimulatory effects of Mn2+ and Mg2+ are additive. These data characterize the existence of two different membrane-bound sphingomyelinases in the seminiferous tubules of the rat.
Raimann
P E
PE
Departamento de Bioquímica, ICBS, UFRGS, Porto Alegre, RS, Brazil.
Custodio de Souza
I C
IC
Bernard
E A
EA
Guma
F C
FC
D000367:Age Factors; D000818:Animals; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008345:Manganese / Q000494:pharmacology*; D008670:Metals / Q000494:pharmacology; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology; D051381:Rats; D017208:Rats, Wistar; D012671:Seminiferous Tubules / Q000187:drug effects / Q000201:enzymology*; D013108:Sphingomyelin Phosphodiesterase / Q000187:drug effects* / Q000378:metabolism*; D013109:Sphingomyelins / Q000378:metabolism
D008670:Metals; D013109:Sphingomyelins; D008345:Manganese; D013108:Sphingomyelin Phosphodiesterase; D008274:Magnesium