Calponin homology (CH) domain | |||||||||||
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![]() Solution structure of calponin homology domain of IQGAP1 [1] | |||||||||||
Identifiers | |||||||||||
Symbol | CH | ||||||||||
Pfam | PF00307 | ||||||||||
InterPro | IPR001715 | ||||||||||
SMART | CH | ||||||||||
PROSITE | PDOC00019 | ||||||||||
SCOP2 | 1aoa / SCOPe / SUPFAM | ||||||||||
CDD | cd00014 | ||||||||||
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Calponin homology domain (or CH domain) is a family of actin binding domains found in both cytoskeletal proteins and signal transduction proteins. [2] The domain is about 100 amino acids in length and is composed of four alpha helices. [3] It comprises the following groups of actin-binding domains:
A comprehensive review of proteins containing this type of actin-binding domains is given in. [4]
The CH domain is involved in actin binding in some members of the family. However, in calponins there is evidence that the CH domain is not involved in its actin binding activity. [5] Most proteins have two copies of the CH domain, however some proteins such as calponin and the human vav proto-oncogene ( P15498 ) have only a single copy. The structure of an example CH domain has been determined using X-ray crystallography. [6]
Human genes encoding calponin homology domain-containing proteins include:
Fimbrin also known as is plastin 1 is a protein that in humans is encoded by the PLS1 gene. Fimbrin is an actin cross-linking protein important in the formation of filopodia.
Actin-binding proteins are proteins that bind to actin. This may mean ability to bind actin monomers, or polymers, or both.
Pleckstrin homology domain or (PHIP) is a protein domain of approximately 120 amino acids that occurs in a wide range of proteins involved in intracellular signaling or as constituents of the cytoskeleton.
Utrophin is a protein that in humans is encoded by the UTRN gene. The name is a short form for ubiquitous dystrophin.
Calponin is a calcium binding protein. Calponin tonically inhibits the ATPase activity of myosin in smooth muscle. Phosphorylation of calponin by a protein kinase, which is dependent upon calcium binding to calmodulin, releases the calponin's inhibition of the smooth muscle ATPase.
Actinin is a microfilament protein. The functional protein is an anti-parallel dimer, which cross-links the thin filaments in adjacent sarcomeres, and therefore coordinates contractions between sarcomeres in the horizontal axis. Alpha-actinin is a part of the spectrin superfamily. This superfamily is made of spectrin, dystrophin, and their homologous and isoforms. In non-muscle cells, it is found by the actin filaments and at the adhesion sites.The lattice like arrangement provides stability to the muscle contractile apparatus. Specifically, it helps bind actin filaments to the cell membrane. There is a binding site at each end of the rod and with bundles of actin filaments.
Protein 4.1,, is a protein associated with the cytoskeleton that in humans is encoded by the EPB41 gene. Protein 4.1 is a major structural element of the erythrocyte membrane skeleton. It plays a key role in regulating membrane physical properties of mechanical stability and deformability by stabilizing spectrin-actin interaction. Protein 4.1 interacts with spectrin and short actin filaments to form the erythrocyte membrane skeleton. Mutations of spectrin and protein 4.1 are associated with elliptocytosis or spherocytosis and anemia of varying severity.
Alpha-actinin-1 is a protein that in humans is encoded by the ACTN1 gene.
Spectrin alpha chain, erythrocyte is a protein that in humans is encoded by the SPTA1 gene.
Alpha II-spectrin, also known as Spectrin alpha chain, brain is a protein that in humans is encoded by the SPTAN1 gene. Alpha II-spectrin is expressed in a variety of tissues, and is highly expressed in cardiac muscle at Z-disc structures, costameres and at the sarcolemma membrane. Mutations in alpha II-spectrin have been associated with early infantile epileptic encephalopathy-5, and alpha II-spectrin may be a valuable biomarker for Guillain–Barré syndrome and infantile congenital heart disease.
Tropomyosin alpha-3 chain is a protein that in humans is encoded by the TPM3 gene.
Ras GTPase-activating-like protein IQGAP1 (IQGAP1) also known as p195 is a ubiquitously expressed protein that in humans is encoded by the IQGAP1 gene. IQGAP1 is a scaffold protein involved in regulating various cellular processes ranging from organization of the actin cytoskeleton, transcription, and cellular adhesion to regulating the cell cycle.
Alpha-actinin-2 is a protein which in humans is encoded by the ACTN2 gene. This gene encodes an alpha-actinin isoform that is expressed in both skeletal and cardiac muscles and functions to anchor myofibrillar actin thin filaments and titin to Z-discs.
Alpha-actinin-4 is a protein that in humans is encoded by the ACTN4 gene.
Spectrin beta chain, brain 1 is a protein that in humans is encoded by the SPTBN1 gene.
Alpha-centractin (yeast) or ARP1 is a protein that in humans is encoded by the ACTR1A gene.
Ena/VASP-like protein is a member of the Ena/VASP family of proteins that in humans is encoded by the EVL gene.
TRIO and F-actin-binding protein is a protein that in humans is encoded by the TRIOBP gene.
WH1 domain is an evolutionary conserved protein domain found on WASP proteins, which are often involved in actin polymerization.
Calponin 1 is a basic smooth muscle protein that in humans is encoded by the CNN1 gene.