Development And Differentiation Enhancing Factor 1 (DDEF1)

Membrane trafficking is regulated in part by small GTP-binding proteins of the ADP-ribosylation factor (ARF) family . ARF function depends on the controlled exchange and hydrolysis of GTP. DDEF1 sequence contains a pleckstrin homology (PH) domain, a zinc finger motif, 3 ankyrin repeats, a proline-rich region containing several SH3 ligand motifs, and an SH3 domain. Northern blot analysis of mouse tissues revealed expression in a variety of tissues. Western blot analysis detected crossreacting proteins, suggesting that ASAP1 is part of a gene family. Studies of the expressed ASAP1 protein showed that it has GAP activity on ARF1 and ARF5 substrates. ASAP1 binds to SH3 domains, including those of SRC and CRK. Both isoforms of ASAP1 became tyrosine phosphorylated by active SRC.