[Cloning and characterization of a novel cardiac-specific kinase gene p93 related to sarcomere].

Myocyte's contraction is regulated by signal transduction pathway composed with many protein factors, but the definite mechanism is still uncertain. A novel cardiac-specific kinase gene which participates in regulation of signal transduction, p93 named, was cloned from adult heart cDNA library. p93, coding a family member of MAPKKK, localized on 1p31.1 based on bioinformatics analyses. Northern blot and 76-tissue array analyses determined that p93 was merely expressed in heart, but was undetectable in other tissues. Immunohistochemical study showed that p93 predominantly localized in the nucleus of cardiac myocytes. In vitro kinase assay indicated that p93 was a functional kinase capable of autophosphorylation. p93 could directly interact with cardiac troponin I by yeast two-hybrid system assessed utilizing bait plasmid containing p93 C-terminus (733 835 aa) and results were further confirmed by co-immunoprecipitation in vivo. Our data suggest that p93 is a cardiac-specific kinase and may play important role in regulation of sarcomeric contraction protein with signal transduction pathway similar ILK.