A determinant in the cytoplasmic tail of the cation-dependent mannose 6-phosphate receptor prevents trafficking to lysosomes.
The bovine cation-dependent mannose 6-phosphate receptor (CD-MPR) is a type 1 transmembrane protein that cycles between the trans-Golgi network, endosomes, and the plasma membrane. When the terminal 40 residues were deleted from the 67-amino acid cytoplasmic tail of the CD-MPR, the half-life of the receptor was drastically decreased and the mutant receptor was recovered in lysosomes. Analysis of additional cytoplasmic tail truncation mutants and alanine-scanning mutants implicated amino acids 34-39 as being critical for avoidance of lysosomal degradation. The cytoplasmic tail of the CD-MPR was partially effective in preventing the lysosomal membrane protein Lamp1 from entering lysosomes. Complete exclusion required both the CD-MPR cytoplasmic tail and transmembrane domain. The transmembrane domain alone had just a minor effect on the distribution of Lamp1. These findings indicate that the cytoplasmic tail of the CD-MPR contains a signal that prevents the receptor from trafficking to lysosomes. The transmembrane domain of the CD-MPR also contributes to this function.
Rohrer
J
J
Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Schweizer
A
A
Johnson
K F
KF
Kornfeld
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D002417:Cattle; D002460:Cell Line; D008247:Lysosomes / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D017527:Receptor, IGF Type 2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D017527:Receptor, IGF Type 2