Localization of m-calpain and calpastatin and studies of their association in pulmonary smooth muscle endoplasmic reticulum
- 作者：Krishna Samanta ; Pulak Kar ; Biswarup Ghosh ; Tapati Chakraborti ; Sajal Chakraborti
- 关键词：m-calpain ; Calpastatin ; Calpain– ; calpastatin association ; Endoplasmic reticulum ; Pulmonary artery ; Smooth muscle
- 刊名：Biochimica et Biophysica Acta (BBA)/General Subjects
- 出版年：2007
- 期刊代码：16_03044165
- 类别：bio
- 出版时间：September 2007
- 卷：1770
- 期：9
- 页码：1297-1307
- 文件大小：1043 K
摘要
Calpain and calpastatin have been demonstrated to play many physiological roles in a variety of systems. It, therefore, appears important to study their localization and association in different suborganelles. Using immunoblot studies, we have identified 80 kDa m-calpain in both lumen and membrane of ER isolated from bovine pulmonary artery smooth muscle. Treatment of the ER with Na2CO3 and proteinase K demonstrated that 80 kDa catalytic subunit and 28 kDa regulatory subunit (Rs) of m-calpain, and the 110-kDa and 70-kDa calpastatin (Cs) forms are localized in the cytosolic side of the ER membrane. Coimmunoprecipitation studies revealed that m-calpain is associated with calpastatin in the cytosolic face of the ER membrane. We have also identified m-calpain activity both in the ER membrane and lumen by casein-zymography. The casein-zymogram has also been utilized to demonstrate differential pattern of the effects of reversible and irreversible cysteine protease inhibitors on m-calpain activity. Thus, a potential site of Cs regulation of m-calpain activity is created by positioning Cs, 80 kDa and 28 kDa m-calpain in the cytosolic face of ER membrane. However, such is not the case for the 80-kDa m-calpain found within the lumen of the ER because of the conspicuous absence of 28 kDa Rs of m-calpain and Cs in this locale.