Abstract
Sarcolemmal fractions of vascular smooth muscles were prepared from porcine thoracic aortae by differential and sucrose density gradient centrifugation. In these fractions, there was a high activity of 5′-nucleotidase, a putative marker enzyme of plasma membrane, and a low activity of rotenone insensitive NADH-cytochrome c reductase a marker of sarcoplasmic reticulum. In these fractions, the Ca 2+ uptake was ATP-dependent. A low concentration of saponin which inhibited Ca 2+ uptake by the plasma membrane but not by the sarcoplasmic reticulum, inhibited 65% of the Ca 2+ uptake of this fraction. The Ca 2+ uptake of this fraction was enhanced by cAMP- and cGMP-dependent protein kinases, and by calmodulin. The cAMP-dependent protein kinase enhanced the phosphorylation of 28 and 22 kDA proteins, while the cGMP-dependent protein kinase phosphorylated the 35 kDa protein. The phosphorylation of 100, 75, 65, 41 and 22 kDa proteins was enhanced by Ca 2+ and calmodulin. These results indicate that cAMP- and cGMP-dependent protein kinases as well as calmodulin play important roles in Ca 2+ transport in the sarcolemma, and that the phosphorylated proteins may be associated with an enhancement of Ca 2+ transport in the sarcolemma.
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: Biochimica et Biophysica Acta (BBA) - Biomembranes
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.
