Is calmodulin an effector protein?
Calmodulin (CaM) is a versatile Ca2+-binding protein that regulates the activity of numerous effector proteins in response to Ca2+ signals.
What type of protein is calmodulin?
Calmodulin is a low molecular weight, acidic, calcium binding protein which mediates the Ca2+ regulation of a wide range of physiological processes throughout eukaryotic organisms.
What uses the protein calmodulin?
Many of the proteins that calmodulin binds are unable to bind calcium themselves, and use calmodulin as a calcium sensor and signal transducer. Calmodulin can also make use of the calcium stores in the endoplasmic reticulum, and the sarcoplasmic reticulum.
Is calmodulin activated by G protein?
G protein-coupled receptor kinases (GRKs) specifically phosphorylate and regulate the activated form of multiple G protein-coupled receptors. These studies suggest that calmodulin may serve a general role in mediating calcium-dependent regulation of GRK activity.
What is calmodulin in smooth muscle?
The principal function of calmodulin in smooth muscle is to activate crossbridge cycling and the development of force in response to a [Ca2+]i transient via the activation of myosin light-chain kinase and phosphorylation of myosin.
What is meant by calmodulin?
: a calcium-binding protein that mediates cellular metabolic processes (such as the contraction of muscle fibers) by regulating the activity of calcium-dependent enzymes.
What protein does calcium bind to in smooth muscle?
calmodulin
Calcium initiates smooth muscle contraction by binding to calmodulin and activating the enzyme myosin light chain kinase. The activated form of myosin light chain kinase phosphorylates myosin on the 20,000-dalton light chain and contractile activity ensues.
Is calmodulin involved in smooth muscle contraction?
Calmodulin, the ubiquitous and multifunctional Ca(2+)-binding protein, mediates many of the regulatory effects of Ca2+, including the contractile state of smooth muscle. A distinct calmodulin-dependent kinase, Ca2+/calmodulin-dependent protein kinase II, has been implicated in modulation of smooth-muscle contraction.
What does calmodulin do in smooth muscle?
How is G protein activated?
G proteins are molecular switches that are activated by receptor-catalyzed GTP for GDP exchange on the G protein alpha subunit, which is the rate-limiting step in the activation of all downstream signaling.
Is calmodulin a hormone?
The importance of calmodulin as a Ca2+-receptor and as a modulator of hormone action and endocrine cells illustrates the pleiotypic nature of this protein in both cellular and molecular aspects of endocrinology.
Is calmodulin attached to the myosin head?
Cloned human nebulin fragments of 7-8 modules bind with high affinity to calmodulin, actin, myosin, and myosin head. Calmodulin reverses the inhibition of ATPase and accelerates actin sliding in calcium-dependent manner. Calmodulin with calcium greatly reduces the binding of nebulin fragments to both actin and myosin.
Which is an intracellular target of calmodulin protein?
Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the binding of Ca2+ is required for the activation of calmodulin.
How many Ca2 + binding sites does calmodulin have?
Calmodulin is a small, highly conserved protein that is 148 amino acids long (16.7 KDa). The protein has two approximately symmetrical globular domains each containing a pair of EF-hand motifs (the N- and C-domain) separated by a flexible linker region for a total of four Ca2+ binding sites.
What is the target conformation of calmodulin peptides?
CALMODULIN TARGET DATABASE It has been shown through numerous structural studies that upon binding its target peptides, CaM forms a compact globular conformation by bending its central helix.
How many methionine residues are found in calmodulin?
A high content of methionine residues (9 out of 148 residues) in calmodulin have been believed to be responsible for the ability to bind numerous target proteins. Indeed, 8 of the 9 methionines are directly involved in binding to all target peptides studied so far by x-ray and NMR.