Rab11positive

Rab11-positive refers to cells, vesicles, or compartments that contain or are defined by the small GTPase Rab11, notably the vertebrate paralogs Rab11a and Rab11b. Rab11 marks a class of endosomes known as recycling endosomes, which mediate the return of internalized membrane proteins to the plasma membrane and coordinate recycling pathways within the cell.

In many cell types, Rab11-positive compartments are located perinuclearly near the recycling endosome system but extend throughout the cytoplasm. In polarized cells such as epithelial and endothelial cells, Rab11 drives the apical or basolateral recycling of receptors and other cargo, aiding membrane homeostasis and signaling. In neurons, Rab11 participates in dendritic trafficking and play roles in synaptic plasticity. Rab11 also has roles in cytokinesis and ciliogenesis and can intersect with autophagy under certain conditions.

Rab11 functions through a network of effectors, notably the Rab11-family interacting proteins (Rab11-FIPs), which help recruit motor proteins and tethering factors to cargo. Motor associations include myosin Vb and components of the dynein-dynactin complex, enabling movement along actin and microtubules. The activity of Rab11 is controlled by guanine nucleotide exchange factors and GTPase-activating proteins that regulate the switch between active GTP-bound and inactive GDP-bound states.

Clinical and research relevance: Rab11-dependent recycling is essential for receptor resensitization, cell signaling, and membrane composition. Disruption of Rab11 pathways can affect trafficking and cell behavior, and several pathogens co-opt Rab11-positive recycling endosomes to promote intracellular transport. Researchers study Rab11-positive compartments using fluorescent Rab11 constructs and Rab11-FIP markers to visualize recycling dynamics.