Interaction of mitogen-activated protein kinases with the kinase interaction motif of the tyrosine phosphatase PTP-SL provides substrate specificity and retains ERK2 in the cytoplasm

ERK1 and ERK2 associate with the tyrosine phosphatase PTP-SL through a kina se interaction motif (KIM) located in the juxtamembrane region of PTP-SL, A glutathione S-transferase (GST)-PTP-SL fusion protein containing the KIM a ssociated with ERK1 and ERK2 as well as with p38/HOG, but not with the rela ted JNK1 kinase or with protein kinase A or C, Accordingly, ERK2 showed in vitro substrate specificity to phosphorylate GST-PTP-SL in comparison with GST-c-Jun, Furthermore, tyrosine dephosphorylation of ERK2 by the PTP-SL De lta KIM mutant was impaired. The in vitro association of ERK1/2 with GST-PT P-SL was highly stable; however, low concentrations of nucleotides partiall y dissociated the ERK1/2 PTP-SL complex. Partial deletions of the KIM abrog ated the association of PTP-SL with ERK1/2, indicating that KIM integrity i s required for interaction. Amino acid substitution analysis revealed that Arg and Leu residues within the KIM are essential for the interaction and s uggested a regulatory role for Ser(231), Finally, coexpression of PTP-SL an d ERK2 in COS-7 cells resulted in the retention of ERK2 in the cytoplasm in a KIM-dependent manner. Our results demonstrate that the noncatalytic regi on of PTP-SL associates with mitogen-activated protein kinases with high af finity and specificity, providing a mechanism for substrate specificity, an d suggest a role for PTP-SL in the regulation of mitogen-activated protein kinase translocation to the nucleus upon activation.