Alpha-protein kinase 3 (ALPK3)

Alpha-protein kinase 3 (ALPK3) is an atypical protein kinase belonging to the alpha-kinase family, characterized by phosphorylation of residues within α-helical regions of target proteins[1][2][3][4][5][6]. ALPK3 localizes predominantly to the M-band of the sarcomere in striated muscle (cardiac and skeletal) and plays a key role in maintaining sarcomere integrity, regulating contractile function, and protein homeostasis via direct phosphorylation of structural proteins and quality control components such as sequestosome-1 (SQSTM1/p62)[1][2][4]. Genetic mutations in ALPK3 are causally linked to familial hypertrophic cardiomyopathy and musculoskeletal defects, and knockout models recapitulate human disease phenotypes with disorganized sarcomeres, impaired contractility, and altered calcium handling[1][4]. Its emerging role as a therapeutic target is based on the evidence that restoring ALPK3-dependent signaling could ameliorate sarcomere-related cardiac diseases[1][4][5]. ALPK3 contains two immunoglobulin-like domains and a catalytic alpha-kinase domain; recent biochemical work suggests it possesses active kinase activity, overturning prior hypotheses that it may function as a pseudokinase[1][2]. Clinical development is limited by a lack of specific inhibitors and safety concerns regarding unnecessary disruption of essential cardiac signaling.

Other names

Alpha kinase 3ALPK3Alpha-protein kinase 3

Not directly targeted by approved drugs. Mechanisms would likely involve kinase inhibition or modulation to restore phosphorylation of sarcomeric/cytoskeletal proteins and correct downstream signaling in diseased myocardium[1][4].