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Investigating the Function of Coronin A in the Early Starvation Response of Dictyostelium discoideum by Aggregation Assays
Published on: June 18, 2016
A developmentally regulated cell surface receptor for a density-sensing factor in Dictyostelium
1Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77251-1892.
The Journal of Biological Chemistry
|March 25, 1994
Summary
Conditioned medium factor (CMF) is crucial for Dictyostelium cell density sensing. Researchers found that the active site is near the N-terminus and identified a specific cell surface receptor for CMF.
Area of Science:
- Cellular and Molecular Biology
- Developmental Biology
- Biochemistry
Background:
- Conditioned medium factor (CMF) is an 80-kDa glycoprotein vital for cell density sensing in developing Dictyostelium discoideum.
- CMF is secreted by starving cells, with its extracellular concentration indicating the density of these cells.
Purpose of the Study:
- To investigate the mechanism of CMF sensing by Dictyostelium cells.
- To characterize the active site and identify the cell surface receptor for CMF.
Main Methods:
- Bacterial synthesis of recombinant CMF and its fragments.
- Binding assays using iodinated recombinant CMF with live Dictyostelium cells.
- Scatchard analysis to determine receptor characteristics.
Main Results:
- Recombinant CMF exhibits activity comparable to native CMF, suggesting glycosylation is not essential for its function.
- The active site of CMF is localized to an 88-amino acid region near the N-terminus.
- A single class of high-affinity receptors (KD = 2.1 nM) for CMF was identified on the surface of starved cells, with maximal binding occurring after 6-8 hours of starvation.
Conclusions:
- CMF is sensed by specific cell surface receptors, and its active site is contained within a defined N-terminal region.
- Receptor binding is specific to starved cells and decreases during later developmental stages.
- CMF is not required for the accumulation of its own receptor, indicating an independent regulatory mechanism.
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