Annexins from bovine adrenal cortex exhibit specific cytosol/membrane solvation

Cytosol/membrane localization of annexins I to VI was analyzed in tissue extracts from bovine adrenal cortex. Based on their solubility in either aqueous or detergents solutions, they were subfractionated in three groups named cytosolic (C), membrane-bound (MB) and membrane-inserted (MI). Less than 1% of the total annexins present in the tissue were recovered in the C fraction when as much as 76.5 and 22.5% were obtained respectively in the MB and the MI fractions. By immunoblotting after SDS-PAGE, it was shown that the various members of the annexin family were not equally recovered in the different fractions. A-V and A-VI were found present in the three fractions whereas the distribution of A-I, A-II, A-III and A-IV was distinct, suggesting different cellular functions.