RALB
Description
The RALB (RAS like proto-oncogene B) is a protein-coding gene located on chromosome 2.
Ras-related protein Ral-B (RalB) is a protein encoded by the RALB gene on human chromosome 2. It is one of two paralogs of the Ral protein, the other being RalA, and is part of the Ras GTPase family. RalA acts as a molecular switch to activate a number of biological processes, mainly cell division and transport, via signaling pathways. Its biological role thus implicates it in many cancers. The Ral isoforms share an 80% overall match in amino acid sequence and 100% match in their effector-binding region. The two isoforms mainly differ in the C-terminal hypervariable region, which contains multiple sites for post-translational modification, leading to diverging subcellular localization and biological function. For example, phosphorylation of Serine 194 on RalA by the kinase Aurora A results in the relocation of RalA to the inner mitochondrial membrane, where RalA helps carry out mitochondrial fission; whereas phosphorylation of Serine 198 on RalB by the kinase PKC results in the relocation of RalB to other internal membranes and activation of its tumorigenic function. RalB is one of two proteins in the Ral family, which is itself a subfamily within the Ras family of small GTPases. As a Ras GTPase, RalB functions as a molecular switch that becomes active when bound to GTP and inactive when bound to GDP. RalB can be activated by RalGEFs and, in turn, activate effectors in signal transduction pathways leading to biological outcomes. For instance, RalB interacts with two components of the exocyst, Exo84 and Sec5, to promote autophagosome assembly, secretory vesicle trafficking, and tethering.
RALB, a multifunctional GTPase, plays a vital role in diverse cellular processes such as gene expression, cell migration, proliferation, oncogenic transformation, and membrane trafficking. Its multiple functions are achieved through interactions with distinct downstream effectors. RALB acts as a GTP sensor for GTP-dependent exocytosis of dense core vesicles. It is crucial for stabilizing the assembly of the exocyst complex and localizing functional exocyst complexes to the leading edge of migrating cells. RALB is essential for suppressing apoptosis. During the late stages of cytokinesis, after the formation of the bridge between dividing cells, RALB mediates exocyst recruitment to the midbody to drive abscission. It is also involved in ligand-dependent receptor-mediated endocytosis of EGF and insulin receptors. RALB interacts with EXOC2/Sec5 and EXOC8/Exo84. It also interacts with RALBP1 through its effector domain.
RALB is also known as -.
