Plasma-membrane-associated protein kinase(s) from normal rat liver phosphorylates exogenous bovine brain calmodulin in the absence of Ca2+ and in the presence of histone or poly(L-lysine). Maximum levels of calmodulin phosphorylation are obtained at a poly(L-lysine)/calmodulin molar ratio of 0.4. Phosphoamino acid analysis revealed that calmodulin is phosphorylated on serine, threonine and tyro...

The interaction of calmodulin with purified guinea pig liver transglutaminase was studied. The nucleotide (ATP and GTP) hydrolysis activity of this tissue transglutaminase was transiently increased and then gradually decreased depending on calmodulin concentration. The peak activation was obtained in the presence of a stoichiometric amount of calmodulin. The effect of calmodulin on the classica...

The importance of guanyl nucleotides for calmodulin stimulation of bovine cerebral cortex adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] was examined by using a partially purified calmodulin-sensitive adenylate cyclase that was resolved from calmodulin-insensitive forms of the enzyme. By using 5'-adenylyl imidodiphosphate as a substrate, in the absence of an ATP-regeneratin...

Effector molecules such as calmodulin modulate the interactions of membrane-associated guanylate kinase homologs (MAGUKs) and other scaffolding proteins of the membrane cytoskeleton by binding to the Src homology 3 (SH3) domain, the guanylate kinase (GK) domain, or the connecting HOOK region of MAGUKs. Using surface plasmon resonance, we studied the interaction of members of all four MAGUK subf...

1. Addition of extracellular pure pig brain calmodulin was found to modulate DNA synthesis and cell proliferation in K562 human leukaemic lymphocytes. At lower cell densities calmodulin significantly stimulated [3H]thymidine uptake; at higher densities it decreased it. 2. A protein biochemically indistinguishable from calmodulin was detected in the cell-conditioned media of rapidly dividing K56...

The binding of Ca(2+)- and Ba(2+)-calmodulin to caldesmon and its functional consequence was investigated with three different calmodulin mutants. Two calmodulin mutants have pairs of cysteine residues substituted and oxidized to a disulphide bond in either the N- or C-terminal lobe (C41/75 and C85/112). The third mutant has phenylalanine-92 replaced by alanine (F92A). Binding measurements in t...

The interaction of calmodulin with calcineurin, a calcium- and calmodulin-stimulated protein phosphatase, was investigated using a solid-phase assay. Binding of 125I-calmodulin by calcineurin immobilized on nitrocellulose membrane filters was of high affinity, reversible, and calcium-dependent. Complex binding kinetics reflected a time- and calcium/calmodulin-dependent conformational change of ...

BACKGROUND Calcium is an important and ubiquitous signalling ion. In most cell types, changes in intracellular calcium concentrations are sensed by calmodulin, a signal transduction protein that regulates cell function through its interactions with kinases and phosphatases. Calcium signals show complex spatiotemporal patterning, but little, if anything, is known about the patterns of calmodulin...

A fluorescent calmodulin derivative, 2-chloro-[4-(epsilon-amino-Lys75)]-[6-(4- diethylaminophenyl)-1,3,5-triazin-4-yl]-calmodulin (TA-calmodulin) [Török and Trentham (1994) Biochemistry 33, 12807-12820], and equilibrium fluorescence methods were used to identify calmodulin-binding domains of connexin subunits of gap junctions. Synthetic peptides corresponding to six extramembrane regions of con...

The role of calmodulin in the activation of Ca 2+-activated Cl  channels (CaCCs) has been an important topic over the past three decades of CaCC research. Recently, the discovery of ANO1/TMEM16 as a component of CaCC raised the question of whether calmodulin modulates ANO1 activity (Tian et al.  permeability of human ANO1 (hANO1) can be dynamically modulated by Ca 2+ /calmodulin (Jung et al.,...