Nebulin^[5] is an actin-binding protein which is localized to the thin filament of the sarcomeres in skeletal muscle. Nebulin in humans is coded for by the gene NEB. 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 and acts as the coats the actin filament.^[6] Other functions of nebulin, such as a role in cell signaling, remain uncertain.

Quick Facts NEB, Available structures ...

NEB
Available structures PDB Human UniProt search: PDBe RCSB List of PDB id codes 1NEB, 1ARK
Identifiers
Aliases	NEB, nebulin, NEB177D, NEM2, AMC6
External IDs	OMIM: 161650 MGI: 97292 HomoloGene: 136285 GeneCards: NEB
Gene location (Human) Chr. Chromosome 2 (human)[1] Band 2q23.3 Start 151,485,336 bp[1] End 151,734,487 bp[1]
Gene location (Mouse) Chr. Chromosome 2 (mouse)[2] Band 2 C1.1|2 29.98 cM Start 52,136,647 bp[2] End 52,378,474 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in biceps brachii tibialis anterior muscle gastrocnemius muscle deltoid muscle triceps brachii muscle quadriceps femoris muscle vastus lateralis muscle body of tongue thoracic diaphragm gallbladder Top expressed in knee joint quadriceps femoris muscle soleus muscle triceps brachii muscle tibialis anterior muscle vastus lateralis muscle skeletal muscle tissue temporal muscle digastric muscle sternocleidomastoid muscle More reference expression data BioGPS n/a
Gene ontology Molecular function actin binding structural constituent of muscle protein binding actin filament binding Cellular component cytoplasm cytosol sarcomere Z disc extracellular exosome cytoskeleton actin cytoskeleton Biological process muscle filament sliding muscle organ development somatic muscle development regulation of actin filament length cardiac muscle thin filament assembly Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 4703 17996 Ensembl ENSG00000183091 ENSMUSG00000026950 UniProt P20929 Q05C45 n/a RefSeq (mRNA) NM_001164507 NM_001164508 NM_001271208 NM_004543 NM_010889 RefSeq (protein) NP_001157979 NP_001157980 NP_001258137 NP_004534 NP_004534.2 n/a Location (UCSC) Chr 2: 151.49 – 151.73 Mb Chr 2: 52.14 – 52.38 Mb PubMed search [3] [4]
Wikidata
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Nebulin has also been shown to regulate actin-myosin interactions by inhibiting ATPase activity in a calcium-calmodulin sensitive manner.^[7]

Mutations in nebulin cause some cases of the autosomal recessive disorder nemaline myopathy.^[8]

A smaller member of the nebulin protein family, termed nebulette, is expressed in cardiac muscle.

The structure of the SH3 domain of nebulin was determined by protein nuclear magnetic resonance spectroscopy.^[9] The SH3 domain from nebulin is composed of 60 amino acid residues, of which 30 percent is in the beta sheet secondary structure (7 strands; 18 residues).

As of 2007, two knockout mouse models for nebulin have been developed to better understand its in vivo function. Bang and colleagues^[10] 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^[11] 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.