clatrinaindependente

Clathrin-independent endocytosis (CIE) refers to a set of cellular pathways that internalize plasma membrane components without forming clathrin-coated pits. In contrast, clathrin-mediated endocytosis (CME) uses clathrin triskelions to sculpt vesicles from the membrane. CIE pathways are diverse and can operate with or without coat proteins, relying on different membrane microdomains, cytoskeletal dynamics, and signaling. In Portuguese, the term clatrinaindependente (or clatrina independente) is used to describe these clathrin-independent processes.

Several major clathrin-independent routes have been identified. Caveolae-mediated endocytosis depends on caveolin-1 and cholesterol-rich caveolae. Flotillin-dependent endocytosis involves flotillin-1/2 and operates independently of clathrin and caveolae. Macropinocytosis is a large-scale, actin-driven uptake mechanism that internalizes extracellular fluid and solutes without clathrin. Fast endophilin-mediated endocytosis (FEME) is another clathrin-independent pathway driven by endophilin and regulated by actin dynamics. Cargoes loaded by CIE pathways include glycosylphosphatidylinositol-anchored proteins, certain receptors, and lipid raft–associated molecules; some toxins and pathogens also exploit clathrin-independent routes.

Cargo selection and regulation of CIE are diverse and context-dependent. These pathways can be constitutive or regulated by signaling events involving small GTPases such as Arf6, Cdc42, and Rac1, as well as by lipid composition and cytoskeletal remodeling. CIE often converges with CME at endosomal compartments and Rab GTPases, contributing to receptor downregulation, lipid uptake, and signaling modulation. Its importance spans normal physiology and disease, including host–pathogen interactions and cellular responses to environmental changes.