Distribution of calcium/calmodulin-dependent protein kinase II in rat ileal enterocytes.
Ca2+/calmodulin (CaM)-dependent protein kinase II is a major effector of the Ca2+ signaling pathway. It has a wide tissue distribution and phosphorylates multiple substrates. Villus enterocytes from rat ileum contain a Ca2+/CaM-dependent kinase activity that phosphorylates the exogenous neural substrate synapsin I. This phosphorylation is blocked by a specific peptide inhibitor. Antibodies made to rat brain Ca2+/CaM-dependent protein kinase II label a single band with a relative molecular mass of approximately 50 kDa in isolated rat enterocytes by immunoblot. Almost one-half of this immunoreactive protein is preferentially found in a particulate compared with a soluble subcellular fraction of the enterocytes. Virtually all of the 50-kDa band in the particulate fraction is insoluble in nonionic detergent, suggesting that the kinase 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 epithelial cells that colocalized with myosin II. This enzyme may have a role in regulating the intestinal epithelial cytoskeleton.
Department of Surgery, Department of Veterans Affairs Hospital, West Haven, Connecticut 06516.
L M
LM
Matovcik
B
B
Haimowitz
J R
JR
Goldenring
A J
AJ
Czernik
F S
FS
Gorelick
D000818:Animals; D000906:Antibodies; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002458:Cell Fractionation; D004847:Epithelial Cells; D004848:Epithelium / Q000201:enzymology; D005455:Fluorescent Antibody Technique; D007082:Ileum / Q000166:cytology / Q000201:enzymology*; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D010449:Peptide Mapping; D010748:Phosphopeptides / Q000302:isolation & purification; D010766:Phosphorylation; D011494:Protein Kinases / Q000032:analysis / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013347:Subcellular Fractions / Q000201:enzymology
D000906:Antibodies; D010748:Phosphopeptides; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases