Hook Homolog 3 (HOOK3)

The deduced 718-amino acid protein has an acidic N-terminal globular domain, an extended central coiled-coil motif, and a basic C-terminal globular domain. HOOK3 shares significant identity with HOOK1, HOOK2, and the Drosophila Hook protein, with highest conservation in the N-terminal domain. Western blot analysis detected HOOK3 in all mouse tissues and human and monkey cell lines examined. Endogenous HOOK3 detected in HEK293 cells had an apparent molecular mass of about 83 kD. Immunolocalization of endogenous HOOK3 in Hep2 cells revealed a perinuclear distribution and colocalization with Golgi marker proteins. Immunogold labeling revealed a polarized distribution of HOOK3 in the Golgi complex, consistent with labeling of the cis face of the Golgi.