Table 2.

Alternatives to the mannose 6-phosphate receptors.

Gene Name	Protein Name	Endosomal Sorting Motif(s)	Endosomal Sorting Mechanism(s)	References
SORT1	Sortilin	YXXφ (YSVL) and dileucine (DDSDEDLI) signals in C-ter region	Direct route: GGA-mediated (dileucine); AP-1-mediated (YXXφ). Indirect route: Clathrin-dependent internalization (YXXφ).	[85,86,87,88,89]
SCARB2	LIMP2	Dileucine signal (DERAPLI) in C-ter region	Direct route: AP-1 and AP-3-mediated via the dileucine motif. Indirect route: minor in some cell types.	[90,91,92,93,94,95]
LDLR	LDL (low-density lipoprotein) receptor	NPXY signal (NPVY) in the C-ter tail	Indirect route: NPXY- and ARH-dependent internalization. Binding to AP-2 reported.	[96,97,98,99]
LRP1	LDL receptor-related protein 1	YXXφ (YATL), NPXY (NPTY and NPVY), dileucine (DDVGGLL and DEKRELL) signals in C-ter region	Indirect route: mediated by YXXφ and dileucine motifs closest to the C-ter end. Minor involvement of the other signals. Binding to AP-2 and clathrin reported.	[100,101]
LRP2	Megalin/low-density lipoprotein receptor-related protein 2	NPXY signals in the C-ter region	Indirect route: NPXY-dependent internalization. Proximal NPXY binds to ARH; distal NPXY binds to Dab2.	[102,103,104]
SEZ6L2	Seizure 6-like protein 2/Brain Specific Receptor-like Protein A (BSRP-A)	YXXφ (YSPI) and NPXY (NPLY) signals in the C-ter region	Direct route: likely YXXφ -mediated; SEZ6L2 detected in AP-1 positive clathrin-coated vesicles. Indirect route: NPXY- and Dab-2 mediated internalization.	[105]
MRC1	Mannose receptor	FENTLY in the C-ter domain	Indirect route: Transmembrane domain and FENTLY-dependent internalization.	[106,107]