Mechanisms and functions of endocytosis in T cells

Table 1 Modes of endocytosis and their salient features

	Actin-dependent	Scale (vesicle diameter)	Canonical cargoes	Cholesterol-dependent	Dynamin-dependent	Cell type first described in
Clathrin-dependent endocytosis	Depends on cell type [2]	35–200 nm [3]	Tfr [4]	Yes [5]	Yes [6, 7]	A. aegypti oocytes [8]
Caveolae-dependent endocytosis	Yes [9,10,11]	50–80 nm [12]	Unclear	Yes [13]	Yes [14]	Murine gall bladder epithelium [15]
CLIC/GEEC pathway endocytosis	Yes [16, 17]	Tubulovesicular, 40 nm width [18]	CTxB, CD44 [19]	Yes [16]	No [20]	COS, CHO cells [21]
Flotillin-dependent endocytosis	Unclear [22]	Unclear	Unclear	Yes [23]	Unclear	HeLa cells [24]
IL-2Rβ pathway endocytosis	Yes [25]	50–100 nm [25, 26]	IL-2Rβ [26]	Yes [27, 28]	Yes [29]	IARC 301.5, YT2C2, CIAC cells [30]
Arf6-dependent endocytosis	Yes [31]	60–200 nm	MHC-I, CD59 [32]	Yes [32]	Unclear	CHO cells [33]
Phagocytosis	Yes [34, 35]	0.5–3 μm [36,37,38,39]	Microbial pathogens	Yes [40, 41]	Yes [42]	Ranine phagocytes [43]
Fast endophilin-mediated endocytosis (FEME)	Yes [44]	Tubulo-vesicular, 100 nm–μm length	β1AR [44, 45]	Yes [44]	Yes [44]	BSC1, HEK293 cells [44]
Activity-dependent bulk endocytosis (ADBE)	Yes [46, 47]	150 nm	VAMP4 [48]	Yes [49]	Yes [50]	Murine cerebellar granule cells [51]
Ultrafast endocytosis (UFE)	Yes [52]	60–80 nm [52, 53]	Unclear	Yes [54]	Yes [52]	Nematode neurons [55]
Massive endocytosis (MEND)	No [56, 57]	< 100 nm [57]	Phospholemman, polypalmitoylated proteins [58]	Yes [59]	No [56, 57]	BHK, HEK293 cells [57]
Macropinocytosis	Yes [60, 61]	200 nm–20 μm	Non-selective	Yes [62, 63]	Unclear	Murine sarcoma cells [64]

Note that actin-dependency, dynamin-dependency, and canonical cargoes remain to be clarified for multiple pathways

ISSN: 1478-811X