Rabproteiineissa

Rabproteiineissa are a conserved family of small GTPases that regulate vesicular transport in eukaryotic cells. They act as molecular switches controlling vesicle budding, movement, docking, and fusion across the endomembrane system. Across species, the Rab family comprises dozens of members, each associated with a particular membrane compartment.

Biochemical properties: Rabproteiineissa are approximately 20–25 kDa GTPases that cycle between a GTP-bound active state and a GDP-bound inactive state. Activation is driven by guanine nucleotide exchange factors (GEFs), while inactivation is mediated by GTPase activating proteins (GAPs). GDP-dissociation inhibitors (GDIs) help extract Rab proteins from membranes when needed. Membrane association is achieved by post-translational prenylation, typically geranylgeranylation at a C-terminal motif, targeting Rab proteins to specific membranes.

Function and localization: Rabproteiineissa recruit specific effectors, including tethering factors, motor proteins, and SNARE adaptors, to control vesicle docking and fusion. Well-studied examples include Rab5 (early endosomes), Rab7 (late endosomes/lysosomes), Rab11 (recycling endosomes), Rab1 (ER-to-Golgi transport), and Rab27 (secretory pathways). The precise localization and Rab-effector interactions ensure directional traffic and maintenance of organelle identity.

Regulation and significance: Rabproteiineissa-mediated trafficking is essential for development and cellular homeostasis. Dysregulation or mutations in Rab proteins can contribute to diseases such as neurodegeneration, immune dysfunction, and cancer. Research on Rabproteiineissa combines genetics, biochemistry, and live-cell imaging to map trafficking routes and understand membrane organization.