A SMAP gene family encoding ARF GTPase-activating proteins and its implication in membrane trafficking.

SMAP1 and SMAP2 proteins constitute a subfamily of the Arf-specific GTPase-activating proteins. Both SMAP proteins bind to clathrin heavy chains and are involved in the trafficking of clathrin-coated vesicles. In cells, SMAP1 regulates Arf6-dependent endocytosis of transferrin receptors from the coated pits of the plasma membrane, whereas SMAP2 regulates Arf1-dependent retrograde transport of TGN38 from the early endosome to the trans-Golgi network.