ley, and Adjunct Professor of Biochemistry and 
Biophysics at the University of California School 
of Medicine, San Francisco. 
Articles 
Baker, N.E., Moses, K., Nakahara, D., Ellis, M.C., 
Carthew, R.W., and Rubin, G.M. 1992. Muta 
tions on the second chromosome affecting the 
Drosophila eye. f Neurogenet 8:85-100. 
Baker, N.E., and Rubin, G.M. 1992. Ellipse muta- 
tions in the Drosophila homologue of the EGF 
receptor affect pattern formation, cell division, 
and cell death in eye imaginal discs. Dev Biol 
150:381-396. 
Fischer-Vize, J.A., Vize, P.D., and Rubin, G.M. 
1992. A unique mutation in the Enhancer of split 
gene complex affects the fates of the mystery cells 
in the developing Drosophila eye. Development 
115:89-101. 
Fortini, M.E., Simon, M.A., and Rubin, G.M. 1992. 
Signalling by the sevenless protein tyrosine kinase 
is mimicked by Rasl activation. Nature 355: 
559-561. 
Freeman, M., Klambt, C, Goodman, C.S., and Ru- 
bin, G.M. 1992. The argos gene encodes a diffu- 
sible factor that regulates cell fate decisions in the 
Drosophila eye. Cell 69:963-975. 
Gaul, U., Mardon, G., and Rubin, G.M. 1992. A pu- 
tative Ras GTPase activating protein acts as a nega- 
tive regulator of signalling by the Sevenless recep- 
tor tyrosine kinase. Cell 68:1007-1019. 
Greenwald, I., and Rubin, G.M. 1992. Making a dif- 
ference: the role of cell-cell interactions in estab- 
lishing separate identities for equivalent cells. 
Ce// 68:271-281. 
Hariharan, I.K., Carthew, R.W., and Rubin, G.M. 
1991. The Drosophila Roughened mutation: ac- 
tivation of a rap homolog disrupts eye develop- 
ment and interferes with cell determination. Cell 
67:717-722. 
Hariharan, I.K., Chuang, P.-T., and Rubin, G.M. 
1991 ■ Cloning and characterization of a receptor- 
class phosphotyrosine phosphatase gene ex- 
pressed on central nervous system axons in Dro- 
sophila melanogaster. Proc Natl Acad Sci USA 
88:11266-11270. 
Lai, Z.-C, and Rubin, G.M. 1992. Negative control 
of photoreceptor development in Drosophila by 
the product of the yan gene, an ETS domain pro- 
tein. Cell 70:609-620. 
Mlodzik, M., Hiromi, Y., Goodman, C.S., and Ru- 
bin, G.M. 1992. The presumptive R7 cell of the 
developing Drosophila eye receives positional 
information independent of sevenless, boss and 
sina. Mech Dev il-.^l-il. 
Mullins, M.C., and Rubin, G.M. 1991. Isolation of 
temperature-sensitive mutations of the tyrosine ki- 
nase receptor sevenless {sev) in Drosophila and 
their use in determining its time of action. Proc 
Natl Acad Sci USA 88:9387-9391. 
Neufeld, T P , Carthew, R.W., and Rubin, G.M. 
1991 Evolution of gene position: chromosomal 
arrangement and sequence comparison of the 
Drosophila melanogaster 2ind Drosophila virilis 
sina and Rh4 genes. Proc Natl Acad Sci USA 
88:10203-10207. 
Rubin, G.M. 1991 . Signal transduction and the fate 
of the R7 photoreceptor in Drosophila. Trends 
Genet 1:512-511. 
Simon, MA, Bowtell, D.D.L., Dodson, G.S., Lav- 
erty, T.R., and Rubin, G.M. 1991. Rasl and a 
putative guanine nucleotide exchange factor per- 
form crucial steps in signaling by the Sevenless 
protein tyrosine kinase. Cell 67:701-716. 
MOLECULAR MECHANISM OF TRANSMEMBRANE SIGNAL TRANSDUCTION 
BY G PROTEIN-COUPLED RECEPTORS 
Thomas P. Sakmar, M.D., Assistant Investigator 
The visual proteins transducin and rhodopsin are 
members of a superfamily of related G proteins and 
G protein-coupled receptors. Light-activated rho- 
dopsin catalyzes guanine nucleotide exchange by 
transducin, which ultimately leads to a change in 
membrane cation conductance in the rod cell and a 
neural signal. The visual system provides an excel- 
lent model to study the molecular mechanism of 
transmembrane signal transduction by G protein- 
coupled receptors. 
Current research interests in Dr. Sakmar's labora- 
tory focus on structure-function relationships in 
rhodopsin and transducin. Under investigation are 
the ground state structure of rhodopsin, the interac- 
tions between specific amino acid residues and the 
1 l-c?s-retinal chromophore that control spectral 
NEUROSCIENCE 431 
