The role of Trans Membrane Domains in the sorting of membrane proteins at the Golgi Complex.

HUGO J. F. MACCIONI

Bari

Congreso; 54th International Conference on the Bioscience of Lipids (ICBL); 2013

International Conference on the Bioscience of Lipids (ICBL)

It is still unclear why some proteins that travel along the secretory pathway are retained in the Golgi complex while others follow their way to the plasma membrane (PM). Recent bioinformatic analyses on a large number of single spanning membrane proteins support the hypothesis that specific features of the Trans-Membrane Domain (TMD) may be relevant to the sorting of these proteins to particular organelles. Here we experimentally test this hypothesis for Golgi and plasma membrane (PM) proteins. Using the Golgi SNARE (Soluble NSF Attachment Protein Receptor) Sft1 and the PM SNARE Sso1 from Saccharomyces cerevisiae as model proteins, we modified the length of their TMDs and the volume of their exoplasmic hemi-TMD, and determined their subcellular localization both in yeast and mammalian cells. We found that short TMDs with voluminous exoplasmic hemi-TMDs confer Golgi membrane residence, while those having less voluminous exoplasmic hemi-TMDs and/or long TMDs confer PM residence to these proteins. Our results indicate that both length and volume of TMDs are major determinants for retention in the Golgi or exit to the PM of Type II membrane proteins.