GTPase-activating protein (GAP) specific for RAB27A and RAB35 (PubMed:16923811, PubMed:30905672). Does not show GAP activity for RAB2A, RAB3A and RAB4A (PubMed:16923811). {ECO:0000269|PubMed:16923811, ECO:0000269|PubMed:30905672}. This is the function of TBC1D10A (TBC1 domain family member 10A, Ensembl gene identifier ENSG00000099992).