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#protein kinase C

3 public questions tagged with this topic.

Membrane Transportation

The regulatory (R) domain of CFTR is phosphorylated by:

Regulatory R domain of CFTR spanning approximately residues 590 to 850 is an intrinsically disordered segment bridging NBD1 and TMD2 containing numerous consensus PKA and PKC phosphorylation sites. Phosphorylation is central to activation. Elevated intracellular cAMP activates protein kinase A which phosphorylates serines including Ser660, Ser737, Ser795, Ser813 and Ser768, neutralizing inhibitory interactions between R domain and NBDs and between NBD1-NBD2 interface. This conformational unblocking permits ATP binding to NBDs, dimer formation, and pore opening. Protein kinase C, Ca2+/calmodulin kinase and Src kinases provide modulatory phosphorylation but PKA is obligatory; non-phosphorylated CFTR remains closed even with ATP present. Dephosphorylation by PP2A and PP2C closes channel. Disease variants lacking PKA sites or with R domain deletions show reduced open probability. Potentiator ivacaftor enhances gating after phosphorylation, illustrating therapeutic relevance of understanding kinase regulation of this atypical ABC channel in epithelial fluid secretion and electrolyte homeostasis. Such detailed mechanistic insight is frequently examined in competitive tests including NEET, CUET, CSIR-NET and GATE where transporter classification, energetics and disease linkage are integrated into problem-solving questions.

Ref: Hwang & Sheppard, Trends Pharmacol Sci 2009, CFTR R domain regulation; Riordan, Annu Rev Biochem 2008.

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A Cell Signaling

PKC activation requires:

Phosphatidylserine, Ca²⁺, DAG, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.

Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)

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Cell Signaling GPCR Pathways - I

DAG mainly activates

Diacylglycerol remains in the plasma membrane after phospholipase C cleavage of PIP2 and recruits conventional and novel isoforms of protein kinase C. Membrane-bound PKC then phosphorylates a wide range of substrates that regulate cell growth, differentiation and metabolism. The simultaneous production of DAG and IP3 therefore coordinates membrane-localized and calcium-dependent branches of the signaling pathway.

Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)

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