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 geneNEB. 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.[6] Other functions of nebulin, such as a role in cell signaling, remain uncertain.
Nebulin has also been shown to regulate actin-myosin interactions by inhibiting ATPase activity in a calcium-calmodulin sensitive manner.[7]
^McElhinny AS, Kazmierski ST, Labeit S, Gregorio CC (July 2003). "Nebulin: the nebulous, multifunctional giant of striated muscle". Trends in Cardiovascular Medicine. 13 (5): 195–201. doi:10.1016/S1050-1738(03)00076-8. PMID12837582.
^Root DD, Wang K (October 1994). "Calmodulin-sensitive interaction of human nebulin fragments with actin and myosin". Biochemistry. 33 (42): 12581–91. doi:10.1021/bi00208a008. PMID7918483.