Abnormal calcium transport into microsomes of grey platelet syndrome

Calcium uptake into isolated membrane vesicles from two patients with a grey platelet syndrome has been investigated. An increase in calcium transport appears in both patients when compared to controls. Determination of the kinetic parameters of the calcium transport system gave similar apparent affinity for calcium and an increase in the calcium uptake velocity. This increase in calcium transport is correlated with the increase of the associated Ca2+ activated ATPase activity. The results would suggest a new relationship between the ultrastructural and functional abnormalities of the grey platelet syndrome.