Calmodulin binding

Small ubiquitous calcium-binding protein. Calmodulin binds and regulates the activity of many protein targets involved in cellular signal transduction pathways mediated by calcium. Calmodulin is ranked among the most conserved proteins and plays a key role in many cellular processes. 

TPR) domains. PP2B (calcineurin) is a heterodimer of a catalytic A-subunit together with a regulatory, Ca2+-binding B-subunit. The A-subunit additionally carries a calmodulin binding site and an autoinhibitory domain. PP7 also contains EF-hand motifs. Both, PP2B and PP7 are stimulated by Ca2+-ions. 

Finally, a 150 kDa calmodulin binding protein, caldesmon is found bound to actin filaments at low calcium concentrations. The ratio of caldesmon to actin molecules seems to vary from 1 20 in the aorta to as much as 1 200 in chicken gizzard. It has been reported and disputed that caldesmon crosslinks actin filaments into large bundles. 

There are at least five distinct isoforms of plasma membrane Ca -ATPases in mammalian tissues that differ in distribution and C-terminal sequences [34]. The molecular weight of these enzymes is in the range of 127 300-134683 (Table I) and they all contain calmodulin-binding domains [3], in contrast to the much smaller ( 110kDa) SERCA enzymes that are calmodulin independent. 

A significant functional and structural feature of the plasma membrane Ca pumps is the presence of the calmodulin-binding subdomains A and B near the C-terminus (Fig. 3), that imparts calmodulin sensitivity on the Ca transport and ATP hydrolysis [3]. Adjacent to the calmodulin-binding region are two acidic segments (AC) and the P(S) region containing a serine residue that is susceptible to phosphorylation by cAMP-dependent protein kinase [34]. A unique feature of the plasma membrane Ca pump is its activation by acidic phospholipids that are presumed to... 

Volume 139. Cellular Regulators (Part A Calcium- and Calmodulin-Binding Proteins)... 

Romoser, V. A., Hinkle, P. M. and Persechini, A. (1997). Detection in living cells of Ca2+-dependent changes in the fluorescence emission of an indicator composed of two green fluorescent protein variants linked by a calmodulin-binding sequence. A new class of fluorescent indicators. J. Biol. Chem. 272, 13270-4. 

The binding of calcium ion to calmodulin, a major biochemical regulator of ion pumps and receptors, occurs on a time scale about a thousand times shorter than that observed for RNA conformational change. This Ca2+-calmodulin binding, which can be followed successfully by nuclear magnetic resonance (NMR), occurs in about ten milliseconds. 

Ca2+/calmodulin. The effect of calmodulin binding is to increase the affinity of the substrate Ca2+ site by 20- to 30-fold. This highly cooperative activation mechanism makes the PMCAs very sensitive to small changes in [Ca2+]j. A group of at least five PMCAs forms a multigene family. Three isoforms, PMCA1-3, occur in brain and each has a distinct distribution [20]. 

Calcineurin is a heterodimer consisting of a large calmodulin-binding catalytic subunit A (61 kDa) anda Ca2+-dependent subunit B (19 kDa).A diazo-group containing photoreactive CsA (47, Fig. 16) was prepared after binding to cyclophylin and after incubation with calcineurin. Irradiation resulted in specific cross-linking mainly to the subunit B , with some minor interaction to subunit A . 

Minakami, R., Jinnai, N., and Sugiyama, H. (1997) Phosphorylation and calmodulin binding of the metabotropic glutamate receptor subtype 5 (mGluR5) are antagonistic in vitro../. Biol. Chem. 272,20291-20298. 

Nakajima, Y., Yamamoto, T Nakayama, T and Nakanishi, S. (1999) A relationship between protein kinase C phosphorylation and calmodulin binding to the metabotropic glutamate receptor subtype 7. J. Biol. Chem. 274,27573-27577. 

Airas, J. M., Betz, H., and El Far, O. (2001) PKC phosphorylation of a conserved serine residue in the C-terminus of group HI metabotropic glutamate receptors inhibits calmodulin binding. FEBS Lett. 494, 60-63. 

Vig PJS, Desaiah D, Mehrotra BD. 1990a. Chlordecone interaction of calmodulin binding with phosphodiesterase. J Appl Toxicol 10(1) 55-57. 

IQ Short calmodulin-binding motif containing conserved lie and Gin residues E(MFP)B 4(11) 16(32) 1B7T... 

Zn-binding domain, present in CBP/p300 and Dystrophin. In Dystrophin, domain is implicated in Calmodulin binding. Mis-sense mutation of conserved cysteine correlates with Duchenne muscular dystrophy. 

Arazi, T., Sunkar, R., Kaplan, B. and Fromm, FI., 1999, A tobacco plasma membrane calmodulin-binding transporter confers Ni tolerance and Pb " h)fpersensitivity in transgenic plants, 20 171-182. 

TABLE 6.9 Numbering System(s) for Calmodulin-Binding Peptides"... 

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