HOOK is a family of evolutionarily related proteins. This family consists of several HOOK1, 2 and 3 proteins from different eukaryotic organisms. The different members of the human gene family are HOOK1, HOOK2 and

HOOK3 Protein Hook homolog 3 is a protein that in humans is encoded by the ''HOOK3'' gene. Function Hook proteins are cytosolic coiled coil proteins that contain conserved N-terminus, N-terminal domains, which attach to microtubules, and more diverg ...

. Different domains have been identified in the three human HOOK proteins, and it was demonstrated that the highly conserved N-terminal domain mediates attachment to microtubules, whereas the central

coiled coil A coiled coil is a structural motif in proteins in which 2–7 alpha-helices are coiled together like the strands of a rope. (Dimers and trimers are the most common types.) Many coiled coil-type proteins are involved in important biological fu ...

motif mediates homodimerisation and the more divergent

C-terminal The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When the protein is ...

domains are involved in binding to specific organelles ( organelle-binding domains). It has been demonstrated that endogenous HOOK3 binds to Golgi membranes, whereas both HOOK1 and HOOK2 are localised to discrete but unidentified cellular structures. In mice the Hook1 gene is predominantly expressed in the testis. Hook1 function is necessary for the correct positioning of microtubular structures within the haploid germ cell. Disruption of Hook1 function in mice causes abnormal sperm head shape and fragile attachment of the flagellum to the sperm head.

Examples

Proteins containing this domain include: * HOOK1; HOOK2;

References

Protein domains Protein families Membrane proteins {{membrane-protein-stub