Dimerization of protein tyrosine phosphatase sigma governs both ligand binding and isoform specificity.

Signaling through receptor protein tyrosine phosphatases (RPTPs) can influence diverse processes, including axon development, lymphocyte activation, and cell motility. The molecular regulation of these enzymes, however, is still poorly understood. In particular, it is not known if, or how, the dimerization state of RPTPs is related to the binding of extracellular ligands.

Cell surface nucleolin on developing muscle is a potential ligand for the axonal receptor protein tyrosine phosphatase-sigma.

Reversible tyrosine phosphorylation, catalyzed by receptor tyrosine kinases and receptor tyrosine phosphatases, plays an essential part in cell signaling during axonal development. Receptor protein tyrosine phosphatase-sigma has been implicated in the growth, guidance and repair of retinal axons. This phosphatase has also been implicated in motor axon growth and innervation.

Functional proteomic analysis of GS-NS0 murine myeloma cell lines with varying recombinant monoclonal antibody production rate.

We previously compared changes in individual protein abundance between the proteomes of GS-NS0 cell lines with varying rates of cell-specific recombinant monoclonal antibody production (qMab). Here we extend analyses of our proteomic dataset to statistically determine if particular cell lines have distinct functional capabilities that facilitate production of secreted recombinant Mab. We categorized 79 proteins identified by mass spectrometry according to their biological function or location in the cell and statistically compared the relative abundance of proteins in each category between GS-NS0 cell lines with varying qMab.

Proteomic analysis of enriched microsomal fractions from GS-NS0 murine myeloma cells with varying secreted recombinant monoclonal antibody productivities.

The folding, transport and modification of recombinant proteins in the constitutive secretory pathway of eukaryotic cell expression systems are reported to be a bottleneck in their production. We have utilised a proteomic approach to investigate the processes catalysed by proteins constituting the secretory pathway to further our understanding of those processes involved in high-level antibody secretion. We used GS-NS0 cell populations differing in qmAb to prepare enriched microsome fractions from each cell population at mid-exponential growth phase.

PTPsigma promotes retinal neurite outgrowth non-cell-autonomously.

The receptor-like protein tyrosine phosphatase (RPTP) PTPsigma controls the growth and targeting of retinal axons, both in culture and in ovo. Although the principal actions of PTPsigma have been thought to be cell-autonomous, the possibility that RPTPs related to PTPsigma also have non-cell-autonomous signaling functions during axon development has also been supported genetically. Here we report that a cell culture substrate made from purified PTPsigma ectodomains supports retinal neurite outgrowth in cell culture.