Localization of rap1 and rap2 proteins in the gelatinase-containing granules of human neutrophils.

The subcellular localization of rap proteins in resting human neutrophils was investigated by immunoblot analysis with specific anti-rap2 and anti-rap1 antibodies of the membrane proteins obtained from distinct subcellular fractions. Rap2 protein was mainly located in gelatinase-containing granules, whereas rap1 protein was detected both in gelatinase-containing granules and in fractions enriched in plasma membrane. Neither rap1 nor rap2 proteins were found in the cytosol or in azurophilic granules. Rap2B, not rap2A, appeared to be the major rap2 protein in human neutrophils. The identification and subcellular localization of rap1 and rap2 proteins at the membranes of gelatinase-rich granules suggest that these proteins could play a role in the regulation of the rapid and selective mobilization of gelatinase-containing granules in human neutrophils.