Identification of functional PDZ domain binding sites in several human proteins.
TIP-15 was previously identified as a cellular protein that can bind to the C-terminal end of the HTLV-1 Tax protein via its two PDZ domains. The sequence of the N-terminal part of TIP-15 is identical to that of the synaptic protein PSD-95. Both proteins are likely to be produced from the same gene by alternative splicing. Whereas expression of the PSD-95 mRNA was detected only with brain RNAs, that of TIP-15 was detected with RNAs from thymus, brain, skeletal muscle and Jurkat cells. The TIP-15 protein exhibits an apparent molecular weight of 40 kD and is weakly expressed in T cell lines. A two-hybrid screen performed with TIP-15 as bait revealed the presence of a PDZ binding site (PDZ-BS) in the following proteins: Lysyl tRNA synthetase, 6-phosphogluconolactonase (6-GPL), Stress-activated protein kinase 3 (SAPK3), NET-1, Diacylglycerol kinase zeta, MTMR1, MCM7, and hSec8. The sequence at the C-terminal ends of these proteins matches the X-S/T-X-V-COOH consensus previously defined for PDZ-BSs, with the exception of 6-GPL and SAPK3 which include a leucine as the C-terminal residue. For Lysyl tRNA synthetase, NET1, MTMR1 and hSec8, binding to TIP-15 was confirmed by co-immunoprecipitation experiments performed with the extracts of transfected COS7 cells. These results show the existence of functional PDZ-BSs in these proteins, but future studies will be necessary to establish whether or not TIP-15 represents a physiological partner. The significance of the presence of a PDZ-BS in these various proteins is discussed with respect to their function.
Fabre
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Laboratoire de Biologie Moléculaire et Cellulaire, UMR 5665 CNRS-ENSL, Lyon, France.
Reynaud
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Jalinot
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P
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism; D019556:COS Cells; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry; D002352:Carrier Proteins / Q000737:chemistry; D018797:Cell Cycle Proteins / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000737:chemistry; D019852:Diacylglycerol Kinase / Q000737:chemistry; D000076122:Disks Large Homolog 4 Protein; D016356:Gene Products, tax / Q000737:chemistry*; D051528:Guanylate Kinases; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D019169:Jurkat Cells; D008565:Membrane Proteins; D051379:Mice; D064168:Minichromosome Maintenance Complex Component 7; D048291:Mitogen-Activated Protein Kinase 12; D020928:Mitogen-Activated Protein Kinases / Q000737:chemistry; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000737:chemistry; D015513:Oncogene Proteins / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry; D054558:Protein Tyrosine Phosphatases, Non-Receptor; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013569:Synapses / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D033921:Vesicular Transport Proteins; D001616:beta-Galactosidase / Q000378:metabolism
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; C489607:EXOC4 protein, human; D016356:Gene Products, tax; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C099763:NET1 protein, human; D009419:Nerve Tissue Proteins; C490988:Net1 protein, mouse; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D012333:RNA, Messenger; C489608:Sec8l1 protein, mouse; D033921:Vesicular Transport Proteins; C033652:postsynaptic density proteins; D048291:Mitogen-Activated Protein Kinase 12; D019852:Diacylglycerol Kinase; D020928:Mitogen-Activated Protein Kinases; D051528:Guanylate Kinases; D002265:Carboxylic Ester Hydrolases; C022363:6-phosphogluconolactonase; C116467:MTMR1 protein, human; D017027:Protein Tyrosine Phosphatases; D054558:Protein Tyrosine Phosphatases, Non-Receptor; D001616:beta-Galactosidase; C101624:MCM7 protein, human; C491086:Mcm7 protein, mouse; D064168:Minichromosome Maintenance Complex Component 7