Reversible phosphorylation as a molecular switch to regulate plasma membrane targeting of acylated SH4 domain proteins.
Acylated SH4 domains represent N-terminal targeting signals that anchor peripheral membrane proteins such as Src kinases in the inner leaflet of plasma membranes. Here we provide evidence for a novel regulatory mechanism that may control the levels of SH4 proteins being associated with plasma membranes. Using a fusion protein of the SH4 domain of Leishmania HASPB and GFP as a model system, we demonstrate that threonine 6 is a substrate for phosphorylation. Substitution of threonine 6 by glutamate (to mimic a phosphothreonine residue) resulted in a dramatic redistribution from plasma membranes to intracellular sites with a particular accumulation in a perinuclear region. As shown by both pharmacological inhibition and RNAi-mediated down-regulation of the threonine/ serine-specific phosphatases PP1 and PP2A, recycling back to the plasma membrane required dephosphorylation of threonine 6. We provide evidence that a cycle of phosphorylation and dephosphorylation may also be involved in intracellular targeting of other SH4 proteins such as the Src kinase Yes.
Tournaviti
Stella
S
Heidelberg University Biochemistry Center, Heidelberg, Germany.
Pietro
Enrica San
ES
Terjung
Stefan
S
Schafmeier
Tobias
T
Wegehingel
Sabine
S
Ritzerfeld
Julia
J
Schulz
Juliane
J
Smith
Deborah F
DF
Pepperkok
Rainer
R
Nickel
Walter
W
D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics / Q000378:metabolism*; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D011992:Endosomes / Q000378:metabolism / Q000648:ultrastructure; D004791:Enzyme Inhibitors / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D007891:Leishmania / Q000378:metabolism; D008387:Marine Toxins; D009154:Mutation; D010080:Oxazoles / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology*; D051575:Proto-Oncogene Proteins c-yes / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D013912:Threonine / Q000378:metabolism
D000953:Antigens, Protozoan; D004791:Enzyme Inhibitors; C401884:HASPB protein, Leishmania; D008387:Marine Toxins; D010080:Oxazoles; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D013912:Threonine; D018698:Glutamic Acid; C059041:calyculin A; D051575:Proto-Oncogene Proteins c-yes; D010749:Phosphoprotein Phosphatases