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A novel receptor-type protein tyrosine phosphatase with a single catalytic domain is specifically expressed in mouse
W Hendriks1, J Schepens, C Brugman
1Department of Cell Biology and Histology, University of Nijmegen, The Netherlands.
Abstract:
Protein tyrosine phosphatases (PTPases) are important regulatory proteins that, together with protein tyrosine kinases, determine the phosphotyrosine levels in cell signalling proteins. By PCR amplification of mouse brain cDNA fragments encoding the catalytic domains of these enzymes, we identified three novel members of the PTPase gene family. Northern-blot analysis showed that two of these novel clones represent brain-specific PTPases, whereas the third originates from a large-sized mRNA that is more ubiquitously expressed. A full-length cDNA encoding one of the brain-specific PTPases, PTP-SL, was isolated. Sequence analysis revealed a transmembrane PTPase containing a single catalytic phosphatase domain that has 45% homology to a rat cytoplasmic brain-specific PTPase named STEP. This suggests a role for PTP-SL in cell-cell signalling processes in the brain.
Insights
Researchers identified three novel protein tyrosine phosphatase (PTPase) genes in the mouse brain. One novel PTPase, PTP-SL, is brain-specific and may play a role in cell-cell signaling.
Area of Science:
- Biochemistry
- Molecular Biology
- Neuroscience
Background:
- Protein tyrosine phosphatases (PTPases) regulate phosphotyrosine levels, crucial for cell signaling, alongside protein tyrosine kinases.
- Understanding PTPase diversity is key to elucidating complex cellular communication networks.
Purpose of the Study:
- To identify novel PTPase genes within the mouse brain.
- To characterize the expression patterns and potential functions of newly discovered PTPases.
Main Methods:
- Polymerase Chain Reaction (PCR) amplification of mouse brain cDNA to isolate catalytic domains of PTPases.
- Northern-blot analysis to determine mRNA expression patterns of novel PTPase clones.
- Full-length cDNA isolation and sequence analysis of the brain-specific PTPase, PTP-SL.
Main Results:
- Three novel PTPase gene family members were identified through PCR.
- Two novel PTPases were found to be brain-specific, while a third showed broader expression.
- A full-length cDNA for PTP-SL, a brain-specific transmembrane PTPase, was isolated and characterized.
- PTP-SL shares 45% homology with the rat brain-specific PTPase STEP.
Conclusions:
- The discovery of novel PTPases expands the known repertoire of these critical signaling enzymes.
- PTP-SL represents a novel transmembrane PTPase with restricted expression in the brain.
- The homology to STEP suggests PTP-SL's involvement in brain-specific cell-cell signaling pathways.