Premium
The internalization signal and the phosphorylation site of transferrin receptor are distinct from the main basolateral sorting information.
Author(s) -
Dargemont C.,
Le Bivic A.,
Rothenberger S.,
Iacopetta B.,
Kühn L.C.
Publication year - 1993
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1993.tb05816.x
Subject(s) - biology , internalization , transferrin receptor , transferrin , phosphorylation , sorting , microbiology and biotechnology , receptor , biochemistry , computer science , programming language
Wild‐type human transferrin receptor (hTfR), like endogenous canine receptor, is expressed almost exclusively (97%) at the basolateral membrane of transfected Madin‐Darbey canine kidney (MDCK) cells. We investigated the role of two distinct features of the hTfR cytoplasmic domain, namely the endocytic signal and the unique phosphorylation site, in polarized cell surface delivery. Basolateral location was not altered by point mutation of Ser24‐‐>Ala24, indicating that phosphorylation is not involved in vectorial sorting of hTfR. The steady state distribution of hTfR was partially affected by a deletion of 36 cytoplasmic residues encompassing the internalization sequence. However, 80% of the receptors were still basolateral. As assessed by pulse‐chase experiments in combination with biotinylation, newly synthesized wild‐type and deletion mutant receptors were directly sorted to the domain of their steady state residency. Although both receptors could bind human transferrin, endocytosis of the deletion mutant was strongly impaired at either surface. These data indicate that the predominant basolateral targeting signal of hTfR is independent of the internalization sequence.