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. Author manuscript; available in PMC: 2024 Dec 10.
Published in final edited form as: Nat Rev Mol Cell Biol. 2007 Aug 1;8(8):603–12. doi: 10.1038/nrm2216

Figure 3. Proposed classification system for endocytic mechanisms.

Figure 3

A cargo protein can be endocytosed by either clathrin-dependent or clathrin-independent (CI) mechanisms. We propose that the CI pathways can be further categorized first by their dependence on the large GTPase dynamin, and then by other mechanistic components of the internalization pathway. This system is based on the current literature, which shows that interfering with or modifying the function of a particular GTPase affects the internalization or trafficking of one set of CI endocytic markers but not another. See TABLE 1 for endocytic markers that have been studied. The aim of this classification system for CI pathways is to categorize the molecular machinery that is associated with these pathways in the most parsimonious fashion consistent with the current literature. It is not meant to imply that a given GTPase is directly involved in regulating a particular internalization pathway because many other important cellular functions may also be regulated by that GTPase. There may be other, as-yet-unidentified CI pathways.