High impact information on Ralbp1

• RalBP1 binds specifically to the active GTP-bound form of RalA and not to a mutant Ral with a point mutation in its putative effector domain [1].
• Herein we demonstrate that overexpression of cytocentrin inhibits assembly of the mitotic spindle without affecting polymerization or distribution of interphase microtubules [2].
• These results indicate that association of cytocentrin with the centrosome may be essential for a timely separation of the diplosomes [2].
• Cytocentrin is a cytosolic protein that transiently associates with the mitotic spindle poles in early prophase, and dissociates from them after completion of mitosis [2].
• In late anaphase/early telophase cytocentrin dissociates entirely from the mitotic apparatus and becomes temporarily localized with microtubules in the midbody, from which it disappears by late telophase [3].

Biological context of Ralbp1

• We interpret these results to suggest that cytocentrin is a cytoplasmic protein that becomes specifically activated or modified at the onset of mitosis so that it can affiliate with the mitotic poles where it may provide a link between the pericentriolar material and other components of the mitotic apparatus [3].
• During metaphase, cytocentrin is located predominately at the mitotic poles, often appearing as an aggregate of small globular sub-components; it also associates with some polar microtubules [3].

Anatomical context of Ralbp1

• Cytocentrin is a Ral-binding protein involved in the assembly and function of the mitotic apparatus [2].

Associations of Ralbp1 with chemical compounds

• Studies employing G2-synchronized cells and nocodazole demonstrated that cytocentrin can become associated with mitotic centrosomes independently of tubulin polymerization and that microtubules regrow from antigen-containing foci [3].

Other interactions of Ralbp1

• To identify downstream targets that might mediate a Ral-specific function, we used a Saccharomyces cerevisiae-based interaction assay to clone a novel cDNA that encodes a Ral-binding protein (RalBP1) [1].
• Identification of a 102 kDa protein (cytocentrin) immunologically related to keratin 19, which is a cytoplasmically derived component of the mitotic spindle pole [3].

References