Lm. Matovcik et al., DISTRIBUTION OF CALCIUM CALMODULIN-DEPENDENT PROTEIN KINASE-II IN RATILEAL ENTEROCYTES, The American journal of physiology, 264(4), 1993, pp. 1029-1036
Ca2+/calmodulin (CaM)-dependent protein kinase II is a major effector
of the Ca2+ signaling pathway. It has a wide tissue distribution and p
hosphorylates multiple substrates. Villus enterocytes from rat ileum c
ontain a Ca2+/CaM-dependent kinase activity that phosphorylates the ex
ogenous neural substrate synapsin I. This phosphorylation is blocked b
y a specific peptide inhibitor. Antibodies made to rat brain Ca2+/CaM-
dependent protein kinase II label a single band with a relative molecu
lar mass of approximately 50 kDa in isolated rat enterocytes by immuno
blot. Almost one-half of this immunoreactive protein is preferentially
found in a particulate compared with a soluble subcellular fraction o
f the enterocytes. Virtually all of the 50-kDa band in the particulate
fraction is insoluble in nonionic detergent, suggesting that the kina
se is associated with the enterocyte cytoskeleton. Antibodies to Ca2+/
CaM-dependent protein kinase II immunocytochemically detect fibrillar
structures concentrated in the terminal web region of intestinal epith
elial cells that colocalized with myosin II. This enzyme may have a ro
le in regulating the intestinal epithelial cytoskeleton.