Oncogenic K-Ras segregates at spatially distinct plasma membrane signaling platforms according to its phosphorylation status

• DOI: 10.1242/jcs.123737
• Publication Date: 2013-08-14T01:17:37Z
• Authors: Carles Barceló; Noelia Paco; Alison J. Beckett; Blanca Alvarez-Moya; Eduard Garrido; Mariona Gelabert; Francesc Tebar; Montserrat Jaumot; Ian Prior; Neus Agell
• Keywords: Nanoclusters; Phosphoprotein

Activating mutations in the K-Ras small GTPase are extensively found human tumors. Although these induce generation of a constitutively GTP-loaded, active form K-Ras, phosphorylation at Ser181 within C-terminal hypervariable region can modulate oncogenic function without affecting vitro affinity for its effector Raf-1. In striking contrast, phosphorylated shows increased interaction cells with Raf-1 and p110α, catalytic subunit PI 3-kinase. Because majority is located plasma membrane, different localization this membrane according to status was explored. Density-gradient fractionation absence detergents showed segregation mutants that carry phosphomimetic or unphosphorylatable serine residue (S181D S181A, respectively). Moreover, statistical analysis immunoelectron microscopy both distinct nanoclusters do not overlap. Finally, induction - by activation protein kinase C (PKC) co-clustering mutant, whereas (when PKC inhibited) non-phosphorylated clusters non-phosphorylatable mutant. Most interestingly, 3-kinase (p110α) but nanoclusters. conclusion, our data provide first time evidence PKC-dependent induced spatially that, turn, favor