Myristoylation and Membrane Binding Regulate c-Src Stability and Kinase Activity

Abstract

Myristoylation is critical for membrane association of Src kinases, but a role for myristate in regulating other aspects of Src biology has not been explored. In the c-Abl tyrosine kinase, myristate binds within a hydrophobic pocket at the base of the kinase domain and latches the protein into an autoinhibitory conformation. A similar pocket has been predicted to exist in c-Src, raising the possibility that Src might also be regulated by myristoylation. Here we show that in contrast to the case for c-Abl, myristoylation exerts a positive effect on c-Src kinase activity. We also demonstrate that myristoylation and membrane binding regulate c-Src ubiquitination and degradation. Nonmyristoylated c-Src exhibited reduced kinase activity but had enhanced stability compared to myristoylated c-Src. We then mutated critical residues in the predicted myristate binding pocket of c-Src. Mutation of L360 and/or E486 had no effect on c-Src membrane binding or localization. However, constructs containing a T456A mutation were partially released from the membrane, suggesting that mutagenesis could induce c-Src to undergo an artificial myristoyl switch. All of the pocket mutants exhibited decreased kinase activity. We concluded that myristoylation and the pocket residues regulate c-Src, but in a manner very different from that for c-Abl.Src family kinases (SFKs) are nonreceptor tyrosine kinases that act as key mediators of cellular signal transduction (12).

EGFR inhibition evokes innate drug resistance in lung cancer cells by preventing Akt activity and thus inactivating Ets-1 function

“…TKI-sensitive mutations in EGFR's catalytic domain reportedly confer the capacity to bind to c-Src (18). This binding is thought to activate c-Src by altering its conformation and subsequent phosphorylation status, potentially explaining the activation of c-Src in EGFR-mutated NSCLC cells (19). We evaluated EGFR phosphorylation at Tyr845 and Tyr1068 in HCC827 cells.…”

Allosterische Kinaseinhibitoren

“…Myristoylierung ist eine hauptsächlich kotranslationale kovalente Modifikation, bei der die gesättigte Fettsäure Myristinsäure mit einem Glyzinrest am N-Terminus eines Proteins verbunden wird [19]. Der Prozess der Myristoylierung findet bei mehr als 100 Proteinen statt und lokalisiert Proteine klassischerweise an intrazelluläre Membranen, indem der Myristatrest in die Lipiddoppelschicht inseriert wird [17]. Im Gegensatz dazu ist der Myristatrest von c-ABL intramolekular an dessen eigene Kinasedomäne gebunden (.…”

Association of NMT2 with the acyl-CoA carrier ACBD6 protects the N-myristoyltransferase reaction from palmitoyl-CoA

“…Co-translational N -myristoylation of the glycine +2 residue of nascent peptides, following removal of the initiator methionine by the human N -myristoyltransferase (NMT) enzymes (NMT1 and NMT2), can affect the association of the acyl-proteins with membranes (24)(25)(26). The addition of a 14-carbon long aliphatic tail can act as a lipid anchor and mediates oligomeric assembly and interaction with other proteins.…”