Protein kinase C C1B domain (PKC C1B domain)

The Protein kinase C (PKC) C1B domain is a highly conserved, cysteine-rich structural motif that serves as a primary regulatory site for the second messenger diacylglycerol (DAG) and exogenous ligands such as phorbol esters (UniProt P17252; PMID: 15576552). Found in the regulatory region of conventional and novel PKC isoforms, the C1B domain facilitates the translocation of the enzyme from the cytosol to cellular membranes upon ligand binding (PMID: 22107165). This membrane recruitment is essential for relieving the autoinhibition of the catalytic domain, thereby activating the kinase to phosphorylate substrates involved in cell growth, differentiation, and apoptosis (PMID: 11713445). Dysregulation of PKC signaling through the C1B domain is linked to various diseases, including cancer, where it can modulate tumor progression, and neurodegenerative disorders like Alzheimer's disease (PMID: 26774338). Pharmacological agents such as bryostatin-1 and ingenol mebutate target the C1B domain to either activate or downregulate PKC signaling for therapeutic purposes, although the high conservation of this domain across isoforms presents significant challenges for achieving isoform-specific modulation (PubChem CID 5280757; PMID: 24561207).

Other names

C1B domainPhorbol ester binding domainDiacylglycerol binding domainCysteine-rich domain

Ligand binding to the C1B domain induces a conformational change that promotes PKC translocation to the plasma membrane, leading to kinase activation and subsequent phosphorylation of downstream signaling targets (PMID: 22107165; PMID: 11713445).