Protein oligomerization modulates raft partitioning and apical sorting of GPI-anchored proteins.

Simona Paladino (1, 2) , Daniela Sarnataro (2) , Rudolf Pillich (2) , Simona Tivodar (2) , Lucio Nitsch (2) , Chiara Zurzolo (1, 2)

1 Trafic membranaire et Pathogénèse
2 Dipartimento di Biologia e Patologia Cellulare e Moleculare

An essential but insufficient step for apical sorting of glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) in epithelial cells is their association with detergent-resistant microdomains (DRMs) or rafts. In this paper, we show that in MDCK cells both apical and basolateral GPI-APs associate with DRMs during their biosynthesis. However, only apical and not basolateral GPI-APs are able to oligomerize into high molecular weight complexes. Protein oligomerization begins in the medial Golgi, concomitantly with DRM association, and is dependent on protein-protein interactions. Impairment of oligomerization leads to protein missorting. We propose that oligomerization stabilizes GPI-APs into rafts and that this additional step is required for apical sorting of GPI-APs. Two alternative apical sorting models are presented.

Domains: Life Sciences [q-bio]; Biochemistry, Molecular Biology; Molecular biology

Simona Paladino, Daniela Sarnataro, Rudolf Pillich, Simona Tivodar, Lucio Nitsch, et al.. Protein oligomerization modulates raft partitioning and apical sorting of GPI-anchored proteins.. Journal of Cell Biology, 2004, 167 (4), pp.699-709. ⟨10.1083/jcb.200407094⟩. ⟨pasteur-00167021⟩