PTPRT Gene (Protein Tyrosine Phosphatase Receptor Type T)
Overview
PTPRT (Protein Tyrosine Phosphatase Receptor Type T), also known as RPTPρ or RPTP-Sigma, is a member of the receptor protein tyrosine phosphatase (RPTP) family. It is primarily expressed in the nervous system where it plays critical roles in regulating synaptic connectivity, neuronal migration, and axon guidance [[moll1991]](https://pubmed.ncbi.nlm.nih.gov/1725271/). PTPRT functions as a receptor-type phosphatase that dephosphorylates specific substrates involved in neuronal development and synaptic plasticity [[besco2006]](https://pubmed.ncbi.nlm.nih.gov/16533388/).
PTPRT is unique among RPTPs due to its extended extracellular domain and brain-restricted expression pattern. The protein has emerged as an important regulator of neuronal connectivity and has been implicated in neurodevelopmental disorders and cancer.
Function
Structure
PTPRT consists of:
Extracellular domain: Contains multiple fibronectin type III repeats that mediate cell-cell interactions
Transmembrane domain: Single pass membrane-spanning region
Cytoplasmic domain: Contains two tandem tyrosine phosphatase domains (D1 and D2)
The D1 domain possesses catalytic activity and dephosphorylates substrate proteins, while the D2 domain may regulate substrate specificity or serve as a docking platform for signaling proteins.
Normal Function in the Nervous System
In neurons, PTPRT performs several critical functions:
Synapse Formation and Function PTPRT localizes to postsynaptic sites and regulates synaptic development [[charette2020]](https://pubmed.ncbi.nlm.nih.gov/32061126/):
Controls the formation and maintenance of dendritic spines
Regulates synaptic transmission through modulation of postsynaptic receptors
Coordinates with presynaptic signaling molecules for proper synaptic alignment
Axon Guidance During development, PTPRT directs axon pathfinding [[engel2012]](https://pubmed.ncbi.nlm.nih.gov/22572952/):
Regulates growth cone dynamics
Modulates cytoskeletal organization in response to guidance cues
Coordinates with intracellular signaling pathways
Neuronal Migration PTPRT influences neuronal positioning during cortical development [[stoker2015]](https://pubmed.ncbi.nlm.nih.gov/25287155/):
Modulates adhesion dynamics during migration
Interacts with cytoskeletal regulators
Dendrite Morphogenesis The phosphatase regulates dendritic arborization and branching [[wang2017]](https://pubmed.ncbi.nlm.nih.gov/28294252/):
Controls dendritic tree complexity
Influences spine distribution along dendrites
Signaling Mechanisms
PTPRT dephosphorylates several key substrates:
Fyn kinase: Regulates Src family kinase activity at synapses