Figure 14.

Hypothesis on the function and redox regulation of LMW-PTP in human lens epithelial cells. Growth factor (GF)-mediated mitogenic cell signaling begins by binding at the cell membrane to initiate autophosphorylation (P) at the receptor (R) and downstream target molecules (target-P) from protein tyrosine kinase. GF binding-induced in situ ROS oxidizes active PTP-SH (protein tyrosine phosphatase, such as LMW-PTP) to its inactive form (PTP with-S-S-, S-S-G or S-OH). Inactive PTP is reduced and activated back to PTP-SH by E (regulating enzyme system, such as TTase) to dephosphorylate and inactivate target proteins (target + P), allowing the completion of cell signaling. Reprinted with permission from Xing et al., BBA (2007); Copyright Elsevier 2007 [100].