RAB6 binding domain (RBD) found in kinesin-like protein KIF20B, and similar proteins
KIF20B (also called cancer/testis antigen 90 (CT90), kinesin family member 20B, kinesin-related motor interacting with PIN1, or M-phase phosphoprotein 1 (MPP1)) is a plus-end-directed motor enzyme that is required for completion of cytokinesis. It is required for proper midbody organization and abscission in polarized cortical stem cells. KIF20B plays a role in the regulation of neuronal polarization by mediating the transport of specific cargos. It participates in the mobilization of SHTN1 (shootin 1) and in the accumulation of PIP3 in the growth cone of primary hippocampal neurons in a tubulin and actin-dependent manner. In the developing telencephalon, KIF20B cooperates with SHTN1 to promote both the transition from the multipolar to the bipolar stage and the radial migration of cortical neurons from the ventricular zone toward the superficial layer of the neocortex. KIF20B acts as an oncogene for promoting bladder cancer cell proliferation, apoptosis inhibition, and carcinogenic progression. This model corresponds to a conserved region in KIF20B that shows some sequence similarity to the RAB6 binding domain (RBD) of KIF20A. KIF20A-RBD is a dimer composed of two parallel alpha helices that form a right-handed coiled-coil additionally stabilized by an inter-helical cysteine bridge.