Proteolytic processing of the receptor‐type protein tyrosine phosphatase PTPBR7

• Published in: The FEBS journal Vol. 274; no. 1; pp. 96 - 108
• Main Authors: Dilaver, Gönül, van de Vorstenbosch, Rinske, Tárrega, Céline, Ríos, Pablo, Pulido, Rafael, van Aerde, Karlijn, Fransen, Jack, Hendriks, Wiljan
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.01.2007
• Subjects: Animals; Brain - metabolism; Fluorescent Antibody Technique; Intracellular Signaling Peptides and Proteins - metabolism; Mice; Mice, Inbred C57BL; Neurons; Phosphorylation; post‐translational modification; Protein Isoforms - metabolism; protein phosphorylation; Protein Processing, Post-Translational; protein stability; Protein Tyrosine Phosphatases - metabolism; Proteins; Proteomics; PTPRR; Receptor-Like Protein Tyrosine Phosphatases, Class 7; Recombinant Fusion Proteins - metabolism; Rodents; Signal transduction
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/j.1742-4658.2006.05568.x

The single‐copy mouse gene Ptprr gives rise to different protein tyrosine phosphatase (PTP) isoforms in neuronal cells through the use of distinct promoters, alternative splicing, and multiple translation initiation sites. Here, we examined the array of post‐translational modifications imposed on the PTPRR protein isoforms PTPBR7, PTP‐SL, PTPPBSγ42 and PTPPBSγ37, which have distinct N‐terminal segments and localize to different parts of the cell. All isoforms were found to be short‐lived, constitutively phosphorylated proteins. In addition, the transmembrane isoform, PTPBR7, was subject to N‐terminal proteolytic processing, in between amino acid position 136 and 137, resulting in an additional, 65‐kDa transmembrane PTPRR isoform. Unlike for some other receptor‐type PTPs, the proteolytically produced N‐terminal ectodomain does not remain associated with this PTPRR‐65. Shedding of PTPBR7‐derived polypeptides at the cell surface further adds to the molecular complexity of PTPRR biology.