Nebulin

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nebulin
Identifiers
Symbol	NEB
Alt. Symbols	NEM2
Entrez	4703
HUGO	7720
OMIM	161650
RefSeq	NM_004543
UniProt	P20929
Other data
Locus	Chr. 2 q22

Nebulin is an actin-binding protein which is localized to the I-band the sarcomeres in skeletal muscle. It is a very large protein (600-900 kDa) and binds as many as 200 actin monomers. Because its length is proportional to thin filament length, it is believed that nebulin acts as a thin filament "ruler" and regulates thin filament length during sarcomere assembly.^[1] Other functions of nebulin, such as a role in cell signaling, remain uncertain.

The interaction of nebulin with actin is calcium-calmodulin sensitive.^[1]

Mutations in nebulin cause some cases of the autosomal recessive disorder nemaline myopathy.^[1]

A second smaller isoform of nebulin, termed nebulette, is expressed in cardiac muscle.

Knockout phenotype

As of 2007, two knockout mouse models for nebulin have been developed to better understand its in vivo function. Bang and colleagues^[1] demonstrated that nebulin-knockout mice die postnatally, have reduced thin filament length, and impaired contractile function. Postnatal sarcomere disorganization and degeneration occurred rapidly in these mice, indicating the nebulin is essential for maintaining the structural integrity of myofibrils. Witt and colleagues^[1] had similar results in their mice, which also died postnatally with reduced thin filament length and contractile function. These nebulin-knockout mice are being investigated as animal models of nemaline myopathy.

References

External links

• MeSH nebulin

v • d • e Histology: muscle tissue
skeletal muscle/general	epimysium, fascicle, perimysium, endomysium, muscle fiber (intrafusal, extrafusal), myofibril sarcomere (a, i, and h bands; z and m lines), myofilaments (thin filament/actin, thick filament/myosin, elastic filament/titin, nebulin), tropomyosin, troponin (T, C, I) costamere (dystrophin, α,β-dystrobrevin, syncoilin, synemin/desmuslin, dysbindin, sarcoglycan, dystroglycan, sarcospan), desmin neuromuscular junction, motor unit, muscle spindle, excitation-contraction coupling, sliding filament mechanism myoblast, satellite cell, sarcoplasm, sarcolemma, sarcoplasmic reticulum, T-tubule
cardiac muscle	myocardium, intercalated disc, nebulette
smooth muscle	calmodulin, vascular smooth muscle

Acknowledgement and Attribution Regarding Sources of Content

Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .