Research On A Novel Platelet And T Cell Activation Antigen 1 (PTA1) Ligand By PTA1/Ig Fusion Protein

Platelet and T cell activation antigen 1 (PTA1) was initially reported by Burns in 1985 with the name TLiSA1 (T lineage specific activation antigen 1, TLiSA1 ), and was renamed as PTA1 in 1989 because of its expression on platelet as well. Since 1985, a lot of investigations have been done on PTA1 expression, functions and its relationship with diseases. PTA1 was mainly expressed on activated T cells, platelets and megakaryocytes lineage, taking part in signal transduction of T cell activation and differentiation as well as platelet activation and aggregation. PTA1 mAb (Leo-A1) was found to stimulate activation and aggregation of platelets and inhibit differentiation of CTL. It seems that PTA1 takes part in mechanism of platelet function disorders, autoimmune diseases, transplantation, virus infection diseases and tumors, suggesting that PTA1 plays an important role in immune system and may have a potential application to clinical diagnosis and treatment.In 1997, PTA1 cDNA was cloned from cDNA library of TPA activated Jurkat cells. PTA1 belongs to immunolglublin super family (IgSF) with a 232aa extracellular region, 25aa transmembrane region and 61 intracellular region. Interestingly, PTA1 is the only IgSF member whose extracellular region consists of two IgV-like domains. Recently, the PTA1 homologous cDNA of ape and monkey was cloned in our Lab. Homology analysis showed PTA1 molecules are highly conserved (93%-95%) among human, ape and monkey, suggesting PTA1 may have an important function. Till now, little is known about PTA1 ligand. So, the aim of this paper is to express and purify the PTA1/IgGFc fusion protein as a tool for further research on PTA1 ligand and its function.Firstly, the mRNA from TPA activated Jurkat cells was extracted and used as a template for reverse-transcription. After PCR amplification, a 793bp fragment...