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GPI‐Anchor Dictates Trafficking of Membrane Dipeptidase
Author(s) -
Isguder Sina Zeynep,
Hooper Nigel M.,
Naim Hassan Y.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a610-c
Subject(s) - endoplasmic reticulum , golgi apparatus , lipid microdomain , microbiology and biotechnology , lipid raft , membrane protein , membrane , chemistry , secretory pathway , biochemistry , biology
Lipid rafts are implicated in the trafficking and sorting of several membrane proteins. In particular GPI‐anchored proteins cluster into Triton X‐100 resistant, cholesterol‐ and sphingolipid‐rich membrane microdomains and are sorted to the apical membrane. A growing body of evidences has pointed to the existence of other types of microdomains that are insoluble in detergents, such as Lubrol WX and Tween‐20. Here, we report on the role of lipid rafts formed at early stages in the biosynthesis of membrane dipeptidase (MDP), a GPI‐anchored protein on its trafficking and sorting. Pulse‐chase experiments revealed retarded maturation rate of the GPI‐anchor deficient mutant (MDPΔGPI) as compared to the wild type protein (wtMDP). However, Golgi to cell surface delivery rate did not show a significant difference between the two variants. On the other hand, early biosynthetic forms of wtMDP were partially insoluble with Tween‐20 while MDPΔGPI was completely soluble. The lack of association of MDPΔGPI with detergent‐insoluble microdomains prior to maturation in the Golgi and the concomitant reduction in its trafficking rate strongly suggest the existence of an early sorting mechanism of membrane proteins operating at a level between the endoplasmic reticulum and the cis‐Golgi. This work has been supported by the German Research Council. Sina Zeynep Isgüder is supported by Bayer Health Care.