Rab11

Rab11 is a member of the Rab family of small GTPases that regulate vesicular trafficking. It localizes primarily to recycling endosomes and coordinates the slow recycling pathway that returns internalized membrane proteins and lipids to the cell surface. Rab11 cycles between an active GTP-bound form and an inactive GDP-bound form, with activity governed by guanine nucleotide exchange factors and GTPase-activating proteins. In humans, two main isoforms exist: Rab11a and Rab11b, encoded by RAB11A and RAB11B, with distinct but overlapping tissue distributions.

Rab11 governs trafficking from recycling endosomes to the plasma membrane and thereby controls the recycling of receptors and transporters. It is involved in recycling of the transferrin receptor and can influence the trafficking of glucose transporters such as GLUT4 in adipocytes. In polarized cells, Rab11 supports sorting and delivery of cargo to the apical or basolateral surfaces and participates in transcytosis. During cytokinesis, Rab11-directed recycling endosomes deliver membrane and cargo to the ingressing cleavage furrow, contributing to successful cell division.

Functional specificity is achieved through interactions with effector proteins. A major family of effectors is the Rab11 family–interacting proteins (Rab11-FIPs), including Rab11-FIP1A through Rab11-FIP5, which link Rab11 to distinct trafficking routes. Motor proteins such as myosin Vb (MYO5B) drive actin-based movement of Rab11 endosomes, and components of the exocyst complex participate in tethering Rab11-dependent vesicles at the plasma membrane.

Rab11 remains a focus of study for its roles in receptor recycling, cell polarity, and endosomal trafficking, with conservation across eukaryotes and ongoing work to elucidate its regulatory networks and implications for development and disease.