| First Author | Jurewicz E | Year | 2013 |
| Journal | Biochim Biophys Acta | Volume | 1833 |
| Issue | 3 | Pages | 761-6 |
| PubMed ID | 23266554 | Mgi Jnum | J:199055 |
| Mgi Id | MGI:5500153 | Doi | 10.1016/j.bbamcr.2012.12.010 |
| Citation | Jurewicz E, et al. (2013) CacyBP/SIP as a novel modulator of the thin filament. Biochim Biophys Acta 1833(3):761-6 |
| abstractText | The CacyBP/SIP protein interacts with several targets, including actin. Since the majority of actin filaments are associated with tropomyosin, in this work we characterized binding of CacyBP/SIP to the actin-tropomyosin complex and examined the effects of CacyBP/SIP on actin filament functions. By using reconstituted filaments composed of actin and AEDANS-labeled tropomyosin, we observed that binding of CacyBP/SIP caused an increase in tropomyosin fluorescence intensity indicating the occurrence of conformational changes within the filament. We also found that CacyBP/SIP bound directly to tropomyosin and that these proteins did not compete with each other for binding to actin. Electron microscopy showed that in the absence of tropomyosin CacyBP/SIP destabilized actin filaments, but tropomyosin reversed this effect. Actin-activated myosin S1 ATPase activity assays, performed using a colorimetric method, indicated that CacyBP/SIP reduced ATPase activity and that the presence of tropomyosin enhanced this inhibitory effect. Thus, our results suggest that CacyBP/SIP, through its interaction with both actin and tropomyosin, regulates the organization and functional properties of the thin filament. |
