Calponin

Although the building blocks of the eukaryotic cytoskeleton appear to be ancient, the protein domains interacting with it appear to have emerged more recendy. Several actin-binding domain families, namely calponin homology, CH, actin depolymerisation factor (ADF), the Sla2p... 

A cytoskeletal regulatory protein that attaches laterally to actin filament without resulting in filament cross-linking and/or bundling. These include troponin, tropomyosin, calponin, tropomodulin, adducin, caldesmon, and hisactophilin. See also ABM-1 ABM-2 Sequences in Actin-Based Motors Actin-Based Bacterial Motility Actin Assembly Kinetics... 

Although much of the focus has been on the DPC of striated muscle, it is likely that desmin attachments to dense plaques of smooth muscle play critical roles in regulating the transmission of contractile forces in this tissue as well. This is particularly relevant in light of the observed defects in smooth muscle of desmin-deficient mice, in which active force per cross-sectional area was reduced to 40% of controls of smooth muscle tissue (Sjuve et al, 1998). IFAP candidates for serving this linking function are plectin and other components of the actin-rich cortex, including calponin (which also plays a role in the cytoplasm of smooth muscle cell dense bodies see below), and the spectrin/ankyrin complex. 

Nishida, W., Abe, M., Takahashi, K., and Hiwada, K. (1990). Do thin filaments of smooth muscle contain calponin A new method for the preparation. FEBS Lett. 268, 165-168. 

Wang, P., and Gusev, N. B. (1996). Interaction of smooth muscle calponin and desmin. 

Matsudaira, 1991). These domains have been named calponin homology or CH domains (Castresana and Saraste, 1995) based on the sequence similarity to the smooth muscle regulatory protein calponin (Winder and Walsh,... 

The calponin homology (CH) domain has been identified in many molecules of differing function. However, its presence usually signifies an interaction of some sort with the actin cytoskeleton via an association with F-actin. The domain was initially identified as a 100-residue motif found at the N-terminus of the smooth muscle regulatory protein calponin and, hence, was termed the CH domain (Castresana and Saraste, 1995). The refinement of algorithms for the identification of distinct protein motifs has allowed the identification of CH domains in proteins that range... 

Banuelos, S., Saraste, M., and Carugo, K. D. (1998). Structural comparisons of calponin homology domains Implications for actin binding. Structure 6, 1419-1431. 

Galkin, V. E., Orlova, A., VanLoock, M. S., and Egelman, E. H. (2003). Do the utrophin tandem calponin homology domains bind F-actin in a compact or extended conformation /. Mol. Biol. 331, 967-972. 

Gimona, M., and Mital, R. (1998). The single CH domain of calponin is neither sufficient nor necessary for F-actin binding./. Cell Sci. Ill, 1813-1821. 

Gimona, M., and Winder, S. J. (1998). Single calponin homology domains are not actin-binding domains. Curr. Biol. 8, R674-675. 

Keep, N. H., Norwood, F. L., Moores, C. A., Winder, S. J., and Kendrick-Jones, J. (1999a). The 2.0A structure of the second calponin homology domain from the actin-binding region of the dystrophin homologue utrophin./ Mol. Biol. 285, 1257-1264. 

Fig. 11. The structure of a-actinin and the two vertebrate Z-band lattices. (A) The ubiquitous protein a-actinin is an anti-parallel homodimer. Each 100 KDa monomer comprises four central spectrin repeats (SI to S4) an EF-hand domain and two calponin homology domains (CH) at the N-terminus. The EF-hand domains bind calcium in non-muscle cells. One a-actinin molecule binds two actin filaments via the calponin homology domains. a-Actinin binds titin via EF-hand domains. (B, C) The Z-band is the site where actin filaments from adjacent sarcomeres overlap in a tetragonal lattice and are crosslinked by a-actinin molecules. The polarity and origin of the actin filaments is indicated by U (up) and D (down). The appearance of the Z-band in cross-section is typically basketweave-like (B) or small square-like (G). The appearance is reported to transform between the two appearances depending on the state of the muscle.

LPL M-CSFR MHC MHC-II MMCP MMP NG2 PDGF PPAR RANK Sca-1 SM22 L lipoprotein monocyte - colony stimulation factor receptor myosin heavy chain MHC class II mouse mast cell protease metalloproteinase proteoglycan heparan-sulfate related to pericytes activity platelet-derived growth factor peroxisome proliferator-activated receptor gamma receptor activator of NF-kappa 3 stem cell antigen 1 smooth cell protein structurally related to calponin, both actin and tropomyosin ligands... 

A family of actin-binding proteins that exist in various isoforms. As with other protein isoforms or isoenzymes, the expression of the isoforms is tissue-specific. The interaction of calponin with actin inhibits the actomyosin Mg-ATRase activity. See Winder, S. and Walsh, M., Inhibition of the actinomyosin MgATRase by chicken gizzard calponin. Prog. Clin. Biol. Res. 327, 141-148, 1990 Winder, S.J., Sutherland, C., and Walsh, M.R., Biochemical and functional characterization of smooth muscle calponin, Adv. Exp. Med. Biol. 304, 37-51, 1991 Winder, S.J. and Walsh, M.R., Calponin thin filament-linked regulation of smooth muscle contraction. Cell Signal. 5,677-686,1993 el-Mezgueldi, M., Calponin, Int. J. Biochem. 

Cell Biol. 28, 1185-1189, 1996 Szymanski, P.T., Calponin (CaP) as a latch-bridge protein — a new concept in regulation of contractility in smooth muscle, J. Muscle Res. Cell Motil. 25,7-19,2004 Lehman, W., Craig, R., Kendrick-Jones, J., and Sulherland-Smith, A.J., An open or closed case for the conformation of calponin homology domains on F-actin J. Muscle Res. Cell Motil. 25, 351-358, 2004 Feijani, L, Fattoum, A., Maciver, S.K. et al., A direct interaction with calponin inhibits the actin-nucleating activity of gelsohn, Biochem. J. 396, 461 68, 2006. 

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