CSM News Electronic Edition Volume 2, number 1 January 1, 1994 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 [129.105.233.50], via Gopher at the same address, or by World Wide Web through WWW.acns.nwu.edu. -------------------- MEETING ANNOUNCEMENT -------------------- This year's Dictyostelium meeting is being organized by Bill Loomis and Rick Firtel and will be held at UCSD in La Jolla next August 21-26, 1994. Enclosed is a copy of the ad that will be apearing in Cell this February. We expect to have a fantastic meeting and the La Jolla scene should add to the spirit of the meeting. At the end of August expect great weather and the beach and water should be super. Planned is a banquet at the new UCSD aquarium near the beach and a trip to the San Diego Zoo's world famous Wild Animal Park. We're expecting it to be a combination of great science in a great atmosphere. La Jolla is actually part of the city of San Diego and the campus is only about 20 min from the airport that can be reasily reached from any US city or through any US entry point. We're about 50 km from Mexico. Expect temperatures between 24 and 28 Celsius during the day and about 19-21 in the evening. The cost of the meeting will be approximately $600 and includes the banquet, refreshments, the trip to the Wild Animal Park, housing on the UCSD campus and some meals. The banquet and the Wild Animal Park are on different days and intertwined with the scientific sessions to give plenty of time for people to interact. We're both looking forward to seeing everyone in La Jolla next summer. INTERNATIONAL DICTYOSTELIUM CONFERENCE organized by Richard A. Firtel and William F. Loomis AUGUST 21 TO 26, 1994 U.C.S.D. CAMPUS La Jolla, California Topics: Cytoskeleton Cell Motility Signal Transduction Gene expression Cell-type differentiation Cell adhesion Morphogens Morphogenesis Receptors, kinases, G proteins, Ligands For further information and registration materials please contact: International Dictyostelium Conference, c/o Drs. Firtel and Loomis Center for Molecular Genetics, UCSD, La Jolla CA. 92093-0634. Completed registration forms must be received by June 1, 1994. Abstracts must be received by June 15, 1994. --------- ABSTRACTS --------- A developmentally regulated cell surface receptor for a density sensing factor in Dictyostelium Renu Jain and Richard H. Gomer Howard Hughes Medical Institute and Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77251-1892 J. Biol. Chem, in press Abstract Conditioned medium factor (CMF) is an 80 kD glycoprotein which is the signal in a cell density sensing system used by starving Dictyostelium cells. CMF is slowly secreted by cells when they starve, and the extracellular level of CMF then becomes an indicator of the density of starving cells. To examine how CMF is sensed, we have made bacterially synthesized recombinant CMF and found that it has as much activity as native CMF, indicating that glycosylation is not part of the active site of CMF. Expression of recombinant fragments of CMF indicates that the active site lies within an 88 amino acid region near the N-terminus. To determine whether CMF is sensed by cell surface receptors, we examined binding of iodinated recombinant CMF to live cells. We found saturable binding to six-hour -starved cells at 3.9 x 104 molecules/cell with a KD of 2.1 nM. The binding saturates in 30 minutes, and a Scatchard plot indicates that there is only one class of receptor. The binding is competed off by the addition of either the native or recombinant CMF, or the 88 amino acid active fragment region; no binding competition is seen from the non-active regions or other proteins. Very little binding to vegetative cells is seen, with maximal binding seen in cells starved for 6-8 hours. The amount of cell surface CMF binding then decreases during later development. Normal levels of CMF binding are seen to CMF- cells, indicating that CMF is not required for the accumulation of its own receptor. --------------------------------------------------------------------- [End CSM-News, volume 2, number 1]