Protein Kinase C - Function

Function

A multiplicity of functions have been ascribed to PKC. Recurring themes are that PKC is involved in receptor desensitization, in modulating membrane structure events, in regulating transcription, in mediating immune responses, in regulating cell growth, and in learning and memory. These functions are achieved by PKC mediated phosphorylation of other proteins. However, the substrate proteins present for phosphorylation vary, since protein expression is different between different kinds of cells. Thus, effects of PKC are cell-type specific:

Cell type Organ/system Activators
ligands --> Gq-GPCRs		 Effects
smooth muscle cell (gastrointestinal tract sphincters) digestive system
  • prostaglandin F2α -->
  • thromboxanes
 contraction
smooth muscle cells in:
  • iris dilator muscle (sensory system)
  • urethral sphincter (urinary system)
  • uterus (reproductive system)
  • arrector pili muscles (integumentary system)
  • ureter (urinary system)
  • urinary bladder (urinary system)
 Various
  • adrenergic agonists --> α1 receptor
 contraction
smooth muscle cells in:
  • iris constrictor muscle
  • ciliary muscle
 sensory system acetylcholine --> M3 receptor contraction
smooth muscle cell (vascular) circulatory system
  • 5-HT --> 5-HT2A receptor
  • adrenergic agonists --> α1 receptor
  • vasoconstriction
smooth muscle cell (seminal tract) reproductive system
  • adrenergic agonists --> α1 receptor
 ejaculation
smooth muscle cell (GI tract) digestive system
  • 5-HT --> 5-HT2A or 5-HT2B receptor
  • acetylcholine (ACh) --> M3 receptor
  • contraction
smooth muscle cell (bronchi) respiratory system
  • 5-HT --> 5-HT2A receptor
  • adrenergic agonists --> α1 receptor
  • acetylcholine --> M3 and M1 receptor
 bronchoconstriction
proximal convoluted tubule cell kidney
  • angiotensin II --> AT1 receptor
  • adrenergic agonists --> α1 receptor
  • stimulate NHE3 --> H+ secretion & Na+ reabsorption
  • stimulate basolateral Na-K ATPase --> Na+ reabsorption
neurons in autonomic ganglia nervous system acetylcholine --> M1 receptor EPSP
neurons in CNS nervous system
  • 5-HT --> 5-HT2A receptor
  • acetylcholine --> M1 receptor
  • neuronal excitation (5-HT)
  • memory? (acetylcholine)
platelets circulatory system 5-HT --> 5-HT2A receptor aggregation
ependymal cells (choroid plexus) ventricular system 5-HT --> 5-HT2C receptor ↑cerebrospinal fluid secretion
heart muscle circulatory system
  • adrenergic agonists --> α1 receptor
 positive ionotropic effect
serous cells (salivary gland) digestive system
  • acetylcholine --> M1 and M3 receptors
  • adrenergic agonists --> α1 receptor
  • ↑secretion
  • increase salivary potassium levels.
serous cells (lacrimal gland) digestive system
  • acetylcholine --> M3 receptor
  • ↑secretion
adipocyte digestive system/endocrine system
  • adrenergic agonists --> α1 receptor
  • glycogenolysis and gluconeogenesis
hepatocyte digestive system
  • adrenergic agonists --> α1 receptor
  • glycogenolysis and gluconeogenesis
sweat gland cells integumentary system
  • adrenergic agonists --> α1 receptor
  • ↑secretion
parietal cells digestive system acetylcholine --> M1 receptors ↑ gastric acid secretion

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