CSM-News, Electronic Edition Volume 1, Number 5 12 June 1993 The goal of CSM-News, Electronic Edition is to speed the rate at which research of interest to the Cellular Slime Mold Community is distributed. Please contribute by submitting author lists, title, and abstracts of papers as soon as they are accepted. Abstracts should be submitted by E-mail to r-chisholm@nwu.edu. All abstracts received will also be forwarded to the traditional CSM News for distribution. ========================================================== Abstracts of Recently Accepted Papers. -------------------------------------- Ramachandran Ramalingam, David R. Shaw and Herbert L. Ennis. (Roche Institute of Molecular Biology, Roche Research Center, Nutley, NJ 07110.) Cloning and Functional Expression of a Dictyostelium discoideum Protein Tyrosine Phosphatase. J.Biol.Chem., in press Abstract Using PCR methods we cloned a 1.7 kb cDNA, denoted DdPTPa, that has high homology with other known eukaryotic protein tyrosine phosphatases. DdPTPa possess a 241 amino acid protein tyrosine phosphatase domain located in the C-terminus, which exhibits a 39-43% amino acid sequence identity with published protein tyrosine phosphatases. Absence of a characteristic signal sequence and transmembrane domain suggest that DdPTPa is a non-receptor type cytoplasmic protein tyrosine phosphatase. Southern blot analysis of genomic DNA indicates the presence of a multigene protein tyrosine phosphatase family in Dictyostelium. Northern blot analysis reveals four species of mRNA that hybridize to the DdPTPa probe, at least three of which are developmentally regulated. The entire coding sequence of DdPTPa was subcloned into the pET-15b vector and expressed in Escherichia coli. Affinity-purified DdPTPa protein efficiently dephosphorylates both p-nitrophenyl phosphate and tyrosine-phosphorylated reduced carboxyamidomethylated, and maleylated lysozyme. A Dictyostelium transformant overexpressing DdPTPa does not develop normally. The overexpresser fails to aggregate, in contrast to the control transformant containing vector alone, and after 24 h gives rise to only a few abnormal slugs and small fruiting bodies. --------------------------------------------------------------------------- [End CSM-News.v1.#5]