Dynamic Behaviour of Microtubule Plus End Binding Proteins in Cultured Cells

The cytoskeleton is a network of intracellular protein filaments that constructs and maintains a cellular architecture. Microtubules (MT) are one of the three types of the cytoskeleton, and are essential for cell division, cell migration, vesicle transport and cell polarity [1]. MTs are the polymers of globular a/ß tubulin subunits, which are arranged in a cylindrical tube measuring 24 nm in diameter. MTs are polar structures with a slow growing minus end and fast growing plus end. They are also responsible for various others cell processes, including the beating of cilia and flagella, the transport of membrane vesicles in the cytoplasm, the promotion of extension of the neuronal growth cone. These movements result from the special feature of MTs called dynamic instability [2, 3], or the actions of microtubule motor proteins. The heterogeneous population of microtubule-binding proteins that accumulates mainly at the distal ends of polymerizing MTs can regulate their dynamics [4]. MT plus end binding proteins, also called plus end-tracking proteins (+Tips), are able to “surf “the dynamic ends of MTs [5]. EB1 [6], EB3 [7], APC [8], CLASP2 [9], LIS1 [10, 11], CLIP-170 [12, 13], CLIP 115 [13, 14] and the dynactin complex [15], have recently emerged as MT binding proteins that have been observed on the MT plus ends.