Decreased Ca2(+)-ATPase activity after glycosylation of erythrocyte membranes in vivo and in vitro.
Diabetes
; 39(6): 707-11, 1990 Jun.
Article
en En
| MEDLINE
| ID: mdl-2140803
Erythrocyte membranes drawn from diabetic patients with poor metabolic control have increased protein glycosylation and decreased Ca2(+)-ATPase activity. A significant relationship was found between these two parameters. Similar results were obtained when protein glycosylation and Ca2(+)-ATPase activity were measured in membranes from normal erythrocytes preincubated with glucose. In this condition, both parameters showed a clear time and dose dependence. Incubation of erythrocyte membranes instead of intact erythrocytes with glucose and glucose-6-phosphate strongly suggests that only the glycosylation of the membrane inner-surface proteins can affect Ca2(+)-ATPase activity. The simultaneous presence of 10 mM glucose and 5 mM ATP in the incubation medium did not affect the degree of erythrocyte membrane protein glycosylation but significantly blocked the inhibitory effect of glucose on Ca2(+)-ATPase activity. However, 5 mM ATP only partially blocked the inhibitory effect of 100 mM glucose, suggesting a competitive mechanism of glucose and ATP for the enzyme active site. Our results show that glycosylation of erythrocyte membrane proteins significantly inhibits Ca2(+)-ATPase activity. This effect could contribute to the development of the capillary closure process observed in diabetic patients. Furthermore, it could represent an index of a general impairment of enzyme function arising in cells chronically exposed to high glucose levels.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
ATPasas Transportadoras de Calcio
/
Membrana Eritrocítica
Límite:
Adolescent
/
Adult
/
Female
/
Humans
/
Male
/
Middle aged
Idioma:
En
Revista:
Diabetes
Año:
1990
Tipo del documento:
Article
País de afiliación:
Argentina
Pais de publicación:
Estados Unidos