G-protein-linked signal transduction systems control development in Dictyostelium.
G-protein-linked cAMP receptors play an essential role in Dictyostelium development. The cAMP receptors are proposed to have seven transmembrane domains and a cytoplasmic C-terminal region. Overexpression of the receptor in cells, when the endogenous receptor is not present, results in a 10- to 50-fold increase in cAMP-binding sites. Antisense cell lines, which lack cAMP receptors, do not enter the developmental program. Ligand-induced phosphorylation is proposed to occur on serine and threonine residues in the receptor C-terminus. The kinetics of receptor phosphorylation and dephosphorylation correlate closely with the shift of receptor mobility and the adaptation of several cAMP-induced responses. Two alpha-subunits, G-alpha-1 and G-alpha-2, have been cloned and specific antisera developed against each. Both subunits are expressed as multiple RNAs with different developmental time courses. The mutant Frigid A has a functional defect in G-alpha-2 which prevents it from entering development. We propose that G-protein-linked receptor systems will be a major component in the development of many organisms.
Johnson
R L
RL
Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Gundersen
R
R
Lilly
P
P
Pitt
G S
GS
Pupillo
M
M
Sun
T J
TJ
Vaughan
R A
RA
Devreotes
P N
PN
D000595:Amino Acid Sequence; D004023:Dictyostelium / Q000254:growth & development*; D019204:GTP-Binding Proteins / Q000502:physiology*; D008969:Molecular Sequence Data; D011953:Receptors, Cyclic AMP / Q000502:physiology; D015398:Signal Transduction
D011953:Receptors, Cyclic AMP; D019204:GTP-Binding Proteins