GKAP1 is also called GKAP42. cGMP-dependent protein kinase (cGK) is a major cellular receptor of cGMP, playing important roles in cGMP-dependent signal transduction pathways []. Using the yeast two-hybrid system with cGK-Ialpha as a bait, a male germ- cell-specific 42kDa protein, GKAP42 (42kDa cGMP-dependent protein kinase anchoring protein) has been identified [].The N-terminal 66 amino acids of cGK-Ialpha were shown to be sufficient for association with GKAP42, but GKAP42 did not interact with cGK-Ibeta, cGK-II or cAMP-dependent protein kinase []. GKAP42 mRNA is specifically expressed in testis, where it is restricted to spermatocytes and early-round spermatids []. GKAP42 is believed to function as an anchoring protein for cGK-Ialpha, and it is thought that cGK-Ialpha may participate in germ-cell development through phosphorylation of Golgi-associated proteins such as GKAP42 [].A recurring chromosomal aberration in acute myeloid leukemia (AML) is deletion of the long arm of chromosome 9, del(9q) []. The Commonly Deleted Region (CDR) has been defined to less than 2.4 Mb, and found to contain 7 known genes, including GKAP42. The results of mutation and expression analyses of these genes are consistent with a model of tumour suppression mediated by haploinsufficiency of critical genes in del(9q) AML.
