ホスホマンノース認識系とも言う。
動物レクチンによりリソソーム酵素の細胞内輸送に関与する。
リソソーム酵素はマンノースの6位がリン酸化された高マンノース型糖鎖をもつ。輸送小胞にはマンノース6-リン酸を認識する受容体が存在し、リソソーム酵素溶け都合することで、ゴルジ装置からリソソームに輸送される。
リソソーム内はpHが低いので、受容体は結合が外れ再利用される。
受容体は細胞膜にも存在し、細胞外のリソソーム酵素の取り込みが行われる。
Cation-independent mannose-6-phosphate receptor
Short name=CI Man-6-P receptor
Short name=CI-MPR
Short name=M6PR
Alternative name(s):
300 kDa mannose 6-phosphate receptor
Short name=MPR 300
Insulin-like growth factor 2 receptor
Insulin-like growth factor II receptor
Short name=IGF-II receptor
M6P/IGF2 receptor
Short name=M6P/IGF2R
CD_antigen=CD222
Gene names
Name: IGF2R
Synonyms: MPRI
Function
Transport of phosphorylated lysosomal enzymes from the Golgi complex and the cell surface to lysosomes. Lysosomal enzymes bearing phosphomannosyl residues bind specifically to mannose-6-phosphate receptors in the Golgi apparatus and the resulting receptor-ligand complex is transported to an acidic prelyosomal compartment where the low pH mediates the dissociation of the complex. This receptor also binds IGF2. Acts as a positive regulator of T-cell coactivation, by binding DPP4. Ref.7
Subunit structure
Binds HA-I and HA-II plasma membrane adapters By similarity. Interacts with DPP4; the interaction is direct. Binds GGA1, GGA2 and GGA3. Ref.7 Ref.8
Subcellular location
Lysosome membrane; Single-pass type I membrane protein. Note: Colocalized with DPP4 in internalized cytoplasmic vesicles adjacent to the cell surface. Ref.7
Domain
Contains 15 repeating units of approximately 147 AA harboring four disulfide bonds each. The most highly conserved region within the repeat consists of a stretch of 13 AA that contains cysteines at both ends.
Sequence similarities
Belongs to the MRL1/IGF2R family.
Contains 1 fibronectin type-II domain.
Cation-dependent mannose-6-phosphate receptor
Short name=CD Man-6-P receptor
Short name=CD-MPR
Alternative name(s):
46 kDa mannose 6-phosphate receptor
Short name=MPR 46
Gene names
Name: M6PR
Synonyms: MPR46, MPRD
Function
Transport of phosphorylated lysosomal enzymes from the Golgi complex and the cell surface to lysosomes. Lysosomal enzymes bearing phosphomannosyl residues bind specifically to mannose-6-phosphate receptors in the Golgi apparatus and the resulting receptor-ligand complex is transported to an acidic prelyosomal compartment where the low pH mediates the dissociation of the complex.
Subunit structure
Homodimer. Binds GGA1, GGA2 and GGA3.
Subcellular location
Lysosome membrane; Single-pass type I membrane protein.
Domain
The extracellular domain is homologous to the repeating units (of approximately 147 AA) of the cation-independent mannose 6-phosphate receptor.
Miscellaneous
This receptor has optimal binding in the presence of divalent cations.
