Human biliary epithelial cell line Mz-ChA-1 expresses new isoforms of calmodulin-dependent protein kinase II.
OBJECTIVE
Calmodulin-dependent protein kinase II is a family of closely related multimeric enzymes that regulate a wide variety of cellular processes. In biliary epithelial cells, this kinase seems to regulate Ca(2+)-dependent CI- currents. The aim of this study was to identify isoforms of this kinase expressed in biliary cells.


METHODS
Sequencing of reverse-transcription polymerase chain reaction products identified multiple isoforms in Mz-ChA-1 cells.


RESULTS
Two previously identified isoforms (gamma B and gamma C) and three new isoforms (gamma D, gamma E, and gamma F) of calmodulin-dependent protein kinase II were identified. Each of the novel isoforms contains a unique insert of 114 base pairs in the association region. This insert lies outside the previously identified variable region. In addition, gamma D and gamma F contained other deletions (42 and 69 base pairs, respectively) in the variable region. These isoforms are expressed in a variety of tissues, including biliary epithelial and gallbladder cells, but only gamma C is expressed in rat hepatocytes.


CONCLUSIONS
Identification of these biliary kinase isoforms paves the way for future studies that will elucidate the role of individual isozymes in agonist-stimulated biliary Cl- and fluid secretion.
Kwiatkowski
A P
AP
Department of Medicine, Indiana University School of Medicine, Indianapolis, USA.
McGill
J M
JM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001652:Bile Ducts / Q000201:enzymology*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000302:isolation & purification*; D002460:Cell Line; D004848:Epithelium / Q000201:enzymology; D005704:Gallbladder / Q000201:enzymology; D006801:Humans; D007527:Isoenzymes / Q000302:isolation & purification; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D051381:Rats
D007527:Isoenzymes; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases