kalirin: a bifunctional enzyme with protein kinase activity and guanine-exchange factor (GEF) activity. A protein kinase of the CAMK group. Activates specific Rho GTPase family members, thereby inducing various signaling mechanisms that regulate neuronal shape, growth, and plasticity, through their effects on the actin cytoskeleton. Induces lamellipodia independent of its GEF activity. Genetic variants are associated with susceptibility to coronary heart disease type 5 (CHDS5), a multifactorial disease characterized by an imbalance between myocardial functional requirements and the capacity of the coronary vessels to supply sufficient blood flow. Interacts with the C-terminal of peptidylglycine alpha-amidating monooxygenase (PAM) and with the huntingtin-associated protein 1 (HAP1) Interacts with FASLG. The two GEF domains catalyze nucleotide exchange for RAC1 and RhoA which are bound by DH1 and DH2 respectively. The two GEF domains appear to play differing roles in neuronal development and axonal outgrowth. SH3 1 binds to the first GEF domain inhibiting GEF activity only when in the presence of a PXXP peptide, suggesting that the SH3 domain/peptide interaction mediates binding to GEF1. CRK1 SH3 domain binds to and inhibits GEF1 activity. 6 isoforms of the human protein are produced by alternative splicing. Isoform 2 is brain specific and is highly expressed in cerebral cortex, putamen, amygdala, hippocampus and caudate nucleus. Weakly expressed in brain stem and cerebellum. Isoform 4 is expressed in skeletal muscle.
Protein type: CAMK group; EC 2.7.11.1; GEFs; GEFs, Rac/Rho; Kinase, protein; Protein kinase, CAMK; Protein kinase, Ser/Thr (non-receptor); Trio family
Chromosomal Location of Human Ortholog: 3q21.1-q21.2
Cellular Component: actin cytoskeleton; cytosol
Molecular Function: GTPase activator activity; guanyl-nucleotide exchange factor activity; Rho guanyl-nucleotide exchange factor activity
Biological Process: ephrin receptor signaling pathway; nervous system development; positive regulation of apoptosis; regulation of small GTPase mediated signal transduction; signal transduction; vesicle-mediated transport
Disease: Coronary Heart Disease, Susceptibility To, 5
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