Isoform 2 of Receptor-type tyrosine-protein phosphatase delta

Isoform 2 of PTPRD (receptor-type tyrosine-protein phosphatase delta) is a transmembrane phosphatase that regulates tyrosine phosphorylation signaling in cell-cell interactions and adhesion pathways (UniProt: P23468-2). The full-length protein is 1890 amino acids and 212 kDa. PTPRD is widely expressed across tissues and functions as a negative regulator of receptor tyrosine kinase signaling, with roles in neural development and synaptic plasticity.

In the central nervous system, PTPRD participates in adhesion molecule signaling and axon guidance, processes critical for neural circuit formation and maintenance. The protein interacts with cell adhesion molecules and growth factor receptors at the synapse and cell surface. No disease associations are documented in the UniProt record for this isoform.

In Alzheimer's Disease, PTPRD isoform 2 is significantly downregulated in post-mortem AD brain tissue compared to age-matched controls, with a mean log2 fold-change of −0.52 across subcellular fractions (Chaparral AD proteomics). This downregulation may reflect disrupted phosphatase-mediated signaling in AD pathology, potentially affecting synaptic integrity and receptor signaling homeostasis.