Abstract
We investigated signal transduction between receptor-operated Ca 2+ influx (ROCI) and Src-related nonreceptor protein tyrosine kinase (PTK) in rat pancreatic acini. CCK and the Ca 2+ ionophore enhanced the Src-related PTK activity, whereas the high-affinity CCK-A receptor agonists, fibroblast growth factor (FGF), and the protein kinase C (PKC) activator had no or little effect. This increase was abolished by eliminating [Ca 2+] o, loading of the intracellular Ca 2+ chelator, and administering the PTK inhibitor genistein. While genistein inhibited extracellular Ca 2+ or Mn 2+ entry induced by CCK and carbachol, it did not affect intracellular Ca 2+ release and oscillations. CCK dose-dependently increased the Src phosphotransferase activity, which was abolished by inhibitors of G q protein, phospholipase C (PLC), and Src, but not by the calmodulin kinase (CaMK) inhibitor. Intensities of the Src band and amounts of tyrosine phosphorylated Src were enhanced by CCK stimulation. Thus, Src cascades appear to be coupled to the low-affinity CCK-A receptor and utilize G q-PLC pathways for their activation, independent of PKC and CaMK cascades. The low-affinity CCK-A receptor regulates ROCI via mediation of Src-related PTK and activates Src pathways to cause [Ca 2+] o-dependent pancreatic exocytosis.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Biochemical and Biophysical Research Communications
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
