Hook homolog 1 (h-hook1, hHK1, HOOK1)

Function

• cytoskeletal linker protein
• role in tethering membrane bound organelles to cytoskeleton
• required for spermatid differentiation
  • role in positioning of microtubules of manchette & flagellum in relation to membrane skeleton
• interacts with microtubules, VPS18

Structure

• homodimer, via large coiled coil domain
• belongs to the hook family

Compartment

• cytoplasm
• does not associate with Golgi
• during spermiogenesis, localizes to manchette in spermatids from steps 8-10
• also present between the microtubule manchette & nucleus
• during manchette elongation, preferentially localized to nuclear ring of manchette, localization to manchette decreases
• in more mature spermatids, while manchette migrates posteriorly, it localizes to punctuates spots
• in spermatid differentiation, punctuate expression pattern found at both attachment site & proximal end of elongated manchette
• not present in mature spermatozoa

More general terms

• testis-specific protein
• phosphoprotein

Database

• OMIM: https://mirror.omim.org/entry/607820
• UniProt: http://www.uniprot.org/uniprot/Q9UJC3.html