CSM News Electronic Edition Volume 4, number 4 February 3, 1995 Please submit abstracts of your papers as soon as they have been accepted for publication by sending them to CSM-News@worms.cmsbio.nwu.edu. Back issues of CSM-News, the CSM Reference database and other useful information is available by anonymous ftp from worms.cmsbio.nwu.edu [165.124.233.50], via Gopher at the same address, or by World Wide Web through www.nwu.edu. =============== Announcements =============== Slime Mold Web Page Available ----------------------------- For those of you who use World Wide Web browsers such as Mosaic or Netscape, there is now a Cellular Slime Mold WWW Page. The URL is "http://worms.cmsbio.nwu.edu/dicty.html". Please let us know if there are other things you'd like to see included. Please visit soon. You can read the current or back issues of the CSM News, see the current Email address list, sent mail to the Email list and follow some other links that may be of interest. If you don't know about the World Wide Web, you should find out about it--it is an extremely valuable tool! The Netscape client software for both macintosh and windows can be downloaded from the ftp site in the directory "web clients". Sequences of Dicty Vectors Available ------------------------------------ The sequences of several widely used Dictyostelium vectors are now available on the ftp site or through the Web server. Please let us know if you have sequences for other widely used Dicty vectors that you would like to contribute =========== Abstracts =========== Michael J. Caterina, Dale Hereld, and Peter N. Devreotes. Occupancy of the Dictyostelium cAMP receptor, cAR1, induces a reduction in affinity which depends upon C-terminal serine residues. J. Biol. Chem., in press Summary Many G-protein-coupled receptors display a rapid decrease in ligand binding following pretreatment with agonist. cAR1, a cAMP receptor expressed early in the developmental program of Dictyostelium, mediates chemotaxis, activation of adenylyl cyclase, and gene expression changes which bring about the aggregation of 10^5 amoebae to form a multicellular structure. Occupancy of cAR1 by cAMP initiates multiple desensitization processes, one of which is an apparent reduction in binding sites. In transformed cells expressing cAR1 constitutively, Scatchard analyses revealed that this apparent loss of ligand binding is largely due to a significant reduction in the affinity of cAR1 for cAMP. A parallel increase in the dose-dependence of cAR1-mediated cAMP uptake was observed. Consistent with these findings, proteolysis of intact cells and immunofluorescence suggested that cAR1 remains on the cell-surface following cAMP treatment. Finally, agonist-induced loss of ligand binding is impaired in cAR1 mutants lacking a cluster of cytoplasmic serine residues which are targets of cAMP- induced phosphorylation. --------------------------------------------------------------------- [End CSM-News, volume 4, number 4]