Rabproteiineilla

Rabproteiineilla, also known as Rab proteins, are a family of small GTPases that regulate intracellular vesicle trafficking in eukaryotic cells. They act as molecular switches, cycling between active GTP-bound and inactive GDP-bound states, a process coordinated by guanine-nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). In their inactive form they are often held in the cytosol by GDP dissociation inhibitors (GDIs) and become membrane-associated when activated.

On membranes, Rabproteiineilla recruit effector proteins that drive vesicle budding, movement, docking, and fusion. Each Rab member tends to associate with specific organelles or trafficking routes, helping to define membrane identity. For example, Rab5 functions on early endosomes, Rab7 on late endosomes and lysosomes, Rab11 on recycling endosomes, Rab1 on ER-to-Golgi transport, and Rab3 and Rab27 participate in regulated secretion.

Rab-protein families are highly conserved across eukaryotes and comprise one of the largest small GTPase families; humans express dozens of Rab paralogs. They depend on post-translational prenylation at their C-termini to anchor to membranes, and their localization is dynamically regulated during vesicle life cycles. Studying Rab function employs fluorescent tagging, effector-binding assays, and genetic manipulation to dissect trafficking pathways.

Dysregulation of Rab-mediated trafficking is linked to various diseases and conditions, including neurodegenerative disorders, immune dysfunction, and cancer, highlighting the importance of precise Rab control for cellular homeostasis. Pathogens may exploit Rab pathways to promote infection or replication, illustrating the interplay between host vesicle trafficking and disease.