noun, plural: microtubule-associated proteins
Microtubule-associated proteins (MAPs) are proteins bound to the tubulin subunits of the microtubules in order to regulate their stability. Microtubules are cytoplasmic tubules that serves as the structural component of cytoskeleton, cilia, and eukaryotic flagella. They are made up of polymers of alpha- and beta-tubulin dimers. The binding of the microtubule-associated protein to the tubulin leads to the polymerization of tubulins into microtubule. The proteins may detach from the tubulin through phosphorylation catalyzed by the microtubule-affinity-regulating-kinase (MARK) protein.
Since MAPs are able to regulate the stability of microtubule structure, they are involved in a wide range of functions. They guide the microtubules towards cellular locations. They also mediate the interactions o microtubules with other intracellular proteins.1
MAPs generally fall into two major groups: type I and type II. Type I includes the MAP1 proteins whereas type II includes MAP2 and MAP4.
Abbreviation / Acronym: MAP
1 Cooper, G. M. & Hausman, R. E. (2004) The Cell: A Molecular Approach. ASM Press, Washington D.C.