RESUMO
The microsomal fraction from the log phase of Entamoeba histolytica cells contains Ins(1,4,5)P3 and Ins(1,3,4,5)P4 binding activity. The binding proteins/receptors for both Ins(1,4,5)P3 and Ins(1,3,4,5)P4 were purified and found to be specific for each ligand. The molecular masses for native proteins for InsP3 and InsP4 are 138 kDa and 130 kDa respectively having subunits of 69 kDa and 64 kDa respectively. That these proteins are associated with Ca2+ release was confirmed by including these proteins separately in proteoliposomes and adding InsP3 and InsP4 in both the cases.
Assuntos
Animais , Sítios de Ligação , Cálcio/metabolismo , Canais de Cálcio/isolamento & purificação , Membrana Celular/metabolismo , Entamoeba histolytica/química , Inositol 1,4,5-Trifosfato/metabolismo , Receptores de Inositol 1,4,5-Trifosfato , Fosfatos de Inositol/metabolismo , Peso Molecular , Subunidades Proteicas , Proteolipídeos/metabolismo , Receptores Citoplasmáticos e Nucleares/isolamento & purificaçãoRESUMO
The alpha-amylase enzyme synthesis was higher when M. thermophila D-14 (ATCC 48104) was grown in culture medium incorporated with starch or other carbohydrates containing maltose units. Maximum enzyme production was attained with 1% starch followed by a gradual decrease with increasing concentration. Marked decrease in alpha-amylase synthesis occurred with the addition of glucose to the culture medium and this decreasing activity was proportional to the concentration of glucose. The enzyme synthesis was resumed as soon as the glucose concentration fell below a critical level. The addition of cAMP did not eliminate the repressive activity of glucose. The findings suggest that extracellular alpha-amylase synthesis in M. thermophila D-14 was inducible and subject to catabolite repression.