Artículo
Inhibition of the formation of the spf1p phosphoenzyme by Ca2+
Corradi, Gerardo Raul
; Czysezon, Nicolás Alejandro
; Mazzitelli, Luciana Romina
; Sarbia, Nicolás
; Adamo, Hugo Pedro
Fecha de publicación:
04/2016
Editorial:
American Society for Biochemistry and Molecular Biology
Revista:
Journal of Biological Chemistry (online)
ISSN:
1083-351X
e-ISSN:
0021-9258
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
P5-ATPases are important for processes associated with the endosomal-lysosomal system of eukaryotic cells. In humans, the loss of function of P5-ATPases causes neurodegeneration. In the yeast Saccharomyces cerevisiae, deletion of P5-ATPase Spf1p gives rise to endoplasmic reticulum stress. The reaction cycle of P5-ATPases is poorly characterized. Here, we showed that the formation of the Spf1p catalytic phosphoenzyme was fast in a reaction medium containing ATP, Mg2+, and EGTA. Low concentrations of Ca2+ in the phosphorylation medium decreased the rate of phosphorylation and the maximal level of phosphoenzyme. Neither Mn2+ nor Mg2+ had an inhibitory effect on the formation of the phosphoenzyme similar to that of Ca2+. The Km for ATP in the phosphorylation reaction was 1 μM and did not significantly change in the presence of Ca2+. Halfmaximal phosphorylation was attained at 8 μM Mgμ, but higher concentrations partially protected from Caμ inhibition. In conditions similar to those used for phosphorylation, Ca2+ had a small effect accelerating dephosphorylation and minimally affected ATPase activity, suggesting that the formation of the phosphoenzyme was not the limiting step of the ATP hydrolytic cycle.
Palabras clave:
Atpase
,
Spf1
,
Phosphoenzyme
,
Calcium
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Articulos(IQUIFIB)
Articulos de INST.DE QUIMICA Y FISICO-QUIMICA BIOLOGICAS "PROF. ALEJANDRO C. PALADINI"
Articulos de INST.DE QUIMICA Y FISICO-QUIMICA BIOLOGICAS "PROF. ALEJANDRO C. PALADINI"
Citación
Corradi, Gerardo Raul; Czysezon, Nicolás Alejandro; Mazzitelli, Luciana Romina; Sarbia, Nicolás; Adamo, Hugo Pedro; Inhibition of the formation of the spf1p phosphoenzyme by Ca2+; American Society for Biochemistry and Molecular Biology; Journal of Biological Chemistry (online); 291; 4-2016; 7767-7773
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