Smooth muscle sarcolemma-associated phospholipase C-β2; agonist-evoked translocation

✍ Scribed by Ronald F. Coburn; Edward F. Labelle; Thomas Griffiths II; Carl B. Baron

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 290 KB
• Volume: 171
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/(sici)1097-4652(199706)171:3<271::aid-jcp5>3.0.co;2-l

✦ Synopsis

About 25% of the total cellular PLCb 2 content was found to be associated with a sarcolemmal fraction (SARC) isolated from unstimulated porcine trachealis smooth muscle. SARC-associated PLCb 2 was located within two compartments, a detergent-extractable compartment and a nondetergent extractable compartment. SARC PLCb 2 was measured after extraction with 0.6 M KCl; therefore, PLCb 2 was not bound solely by electrostatic forces within either of these compartments. PLCb 2 was shown to translocate from cytosol to SARC during a 20-sec activation of intact muscle with a muscarinic agonist, carbachol (CARB); i.e., cytosolic total PLCb 2 content decreased significantly to 73 { 7% of control and SARC total PLCb 2 content increased to 180 { 15% of control value. This translocation was maintained at 5 min of CARB. CARBevoked translocation occurred into the detergent-extractable SARC fraction, and PLCb 2 content in this fraction increased 300% compared with that in unstimulated muscle. After CARB, SARC PLCb 2 content accounted for ú50% of total cellular PLCb 2 content. CARB-evoked increase in PLC activity in SARC paralleled the increase in PLCb 2 content. CARB-induced translocations of PLCb 2 from the cytosol to SARC were of a similar magnitude as occurred with phorbol ester-induced translocations of PKCa.