Table 2.
Membrane proteins targeted to the prelysosomal/lysosomal compartment containing uncharged, polar residues in the TM
| Protein | Name and function | Destination | TM sequences | Reference |
|---|---|---|---|---|
| l-MAG (human) | Myelin-associated glycoprotein Adhesion molecule required for maintaining myelin-forming cell-axon contact | Endocytosed and lysosomally degraded in quaking mice | VGAVVAFAILIAICYITQT | (Bo et al., 1995) |
| CD19 (mouse) | CD19 Part of the signal transduction complex in B lymphocytes | Internalized and down-regulated; cytoplasmic tail is not required for internalization | WIVPVVTLVYVIFCMVSLVAFLYC | (Bradbury et al., 1993) |
| CD40L (human, mouse) | CD40L T cell activation molecule associated with T-BAM | Internalized and down-regulated after interaction with CD40 molecules on B cells | IFMYLLTVFLITQMIFSALFAVYL | (Yellin et al., 1994) |
| CD3-δ-γ (human) | CD3 Part of the T cell receptor-signaling complex | Internalized and degraded in the lysosome | PATVAFIIVTDVIATLLLALGVFCFAG | (Letourneur and Klausner, 1992) |
| Interleukin-1 receptor (human) | Interleukin-1 receptor Proliferation of helper T cells (Th2) | Internalized and degraded in the lysosome | HVIGICVTLTVIIVCSVFIY | (Solari et al., 1994) |
| Ii (human) | MHC class II Ii Targets the MHC class II-α-β chains to the lysosomal compartment | Internalized and delivered to the lysosomal compartment | GALYTGFSILVTLLLAGQATTAYFLY | (Bakke and Dobberstein, 1990) |
| Fc receptor (mouse) | Macrophage Fc receptor Clearance of IgG-containing immune complexes | Internalized and delivered to lysosomal compartment after binding polyvalent immune complexes | VLTIVAAVTGIAVAAIVIILVSLVYL | (Mellman and Plutner, 1984) |
| Mannose 6-phosphate receptor (human) | Cation-independent mannose 6-phosphate receptor (IGF receptor) Uptake of lysosomal enzymes | Internalized and is delivered to late endosome; escapes lysosomal targeting because it contains a TGN-sorting signal | AVGAVLSLLLVALTCCLLALLLY | (Oka et al., 1985; Diaz and Pfeffer, 1998) |
| Fibroblast growth factor receptor (human) | Fibroblast growth factor receptor | Internalized and delivered to lysosomal compartment after ligand binding | IIIYCTGAFLISCMVGSVIVY | (Sorokin et al., 1994) |
| Mannose receptor (human) | Macrophage mannose receptor lectin that binds and internalizes proteins containing terminal mannose residues | Internalized; important for delivery of antigens to the antigen-processing compartment | PSSNVAGVVIIVILLILTGAGLAAYFFY | (Wileman et al., 1986; Jiang et al., 1995) |
| Chicken hepatic lectin receptor (chicken) | Chicken liver glycoprotein receptor Lectin | Internalizes and recycles several times before being delivered to the lysosomal compartment | SFAAVYVLLALSFLLLTLLSSVSLA | (Mellow et al., 1988; Graeve et al., 1989) |
| P-selectin (mouse) | Adhesion molecule on activated platelets as a receptor for leukocytes | Internalized and targeted to lysosomes | LTYLGGAVASTTGLEVGGTLLALL | (Green et al., 1994) |