Intra- and intermolecular interactions between intracellular domains of receptor protein-tyrosine phosphatases.
The presence of two protein-tyrosine phosphatase (PTP) domains is a striking feature in most transmembrane receptor PTPs (RPTPs). The generally inactive membrane-distal PTP domains (RPTP-D2s) bind and are proposed to regulate the membrane-proximal PTP domains (RPTP-D1s). We set out to characterize the interactions between RPTP-D1s and RPTP-D2s in vivo by co-immunoprecipitation of hemagglutinin-tagged fusion proteins encoding the transmembrane domain and RPTP-D1 and myc-tagged RPTP-D2. Seven RPTPs from four different subfamilies were used: RPTPalpha, RPTPepsilon, LAR, RPTPvarsigma, RPTPdelta, CD45, and RPTP(mu). We found that RPTP-D2s bound to RPTPs with different affinities. The presence of intrinsic RPTP-D2 altered the binding specificity toward other RPTP-D2s positively or negatively, depending on the identity of the RPTPs. Furthermore, the C terminus of RPTP-D2s and the "wedge" in RPTP-D1s played a central role in binding specificity. Finally, full-length RPTPalpha and LAR heterodimerized in an oxidative stress-dependent manner. Like RPTPalpha-D2, the LAR-D2 conformation was affected by oxidative stress, suggesting a common regulatory mechanism for RPTP complex formation. Taken together, interactions between RPTP-D1s and RPTP-D2s are a common but specific mechanism that is likely to be regulated. The RPTP-D2s and the wedge structures are crucial determinants of binding specificity, thus regulating cross-talk between RPTPs.
Blanchetot
Christophe
C
Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Uppsalalaan 8, Utrecht 3584 CT, The Netherlands.
Tertoolen
Leon G
LG
Overvoorde
John
J
den Hertog
Jeroen
J
D000595:Amino Acid Sequence; D001665:Binding Sites; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D019281:Dimerization; D004735:Energy Transfer; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015151:Immunoblotting; D017493:Leukocyte Common Antigens / Q000737:chemistry*; D008969:Molecular Sequence Data; D010100:Oxygen / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry*; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2; D054630:Receptor-Like Protein Tyrosine Phosphatases, Class 4; D011956:Receptors, Cell Surface; D013050:Spectrometry, Fluorescence; D014162:Transfection
D011956:Receptors, Cell Surface; D006861:Hydrogen Peroxide; D017493:Leukocyte Common Antigens; C516841:PTPRA protein, human; C090899:PTPRD protein, human; C490825:PTPRE protein, human; C516859:PTPRM protein, human; C516883:PTPRS protein, human; D017027:Protein Tyrosine Phosphatases; C516843:Ptpra protein, mouse; C490395:Ptprd protein, mouse; C516860:Ptprm protein, mouse; C516885:Ptprs protein, mouse; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2; D054630:Receptor-Like Protein Tyrosine Phosphatases, Class 4; D010100:Oxygen