Chimeric proteins containing the cytoplasmic domains of the mannose 6-phosphate receptors codistribute with the endogenous receptors.
We have constructed and transiently expressed in HeLa cells a series of hybrid proteins in which the cytoplasmic domain or both the transmembrane and the cytoplasmic domains of the mannose 6-phosphate/insulin-like growth factor II receptor were fused to the ectodomain of the hemagglutinin of the influenza virus (HA), a typical plasma membrane protein. In addition, we have expressed a hybrid protein containing the luminal domain of HA fused to the transmembrane and cytoplasmic tail of the cation-dependent mannose 6-phosphate receptor. These hybrids were transported through and sorted from the secretory pathway as shown by acquisition of endo-H resistant oligosaccharides and their ability to recruit the Golgi assembly proteins AP-1 on the Golgi membrane. Like the mannose 6-phosphate receptors (MPRs), these hybrid proteins are also present in small amounts at the cell surface where they are likely to undergo endocytosis as disruption of the endocytosis signals contained in the MPR cytoplasmic domains induces their accumulation at the cell surface. Double immunofluorescence studies indicate that these chimeras codistribute with the endogenous MPRs at steady state. The results suggest that the cytoplasmic domains of the MPRs are sufficient to determine the steady-state distribution of the full-length proteins.
Mauxion
F
F
European Molecular Biology Laboratory, Heidelberg, Germany.
Schmidt
A
A
Le Borgne
R
R
Hoflack
B
B
D001483:Base Sequence; D003593:Cytoplasm / Q000737:chemistry*; D006367:HeLa Cells; D006389:Hemagglutinins, Viral / Q000737:chemistry*; D006801:Humans; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D017527:Receptor, IGF Type 2 / Q000737:chemistry*; D011956:Receptors, Cell Surface / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000737:chemistry*; D015398:Signal Transduction / Q000502:physiology
D006389:Hemagglutinins, Viral; D017527:Receptor, IGF Type 2; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins