by various protein kinases serves to integrate the ef- 
fects of convergent regulatory pathways on synaptic 
transmission. Moreover, these resuks suggest that 
protein phosphorylation is a major molecular mech- 
anism for the regulation of neurotransmitter recep- 
tors and ion channel function and thus may play a 
primary role in the regulation of synaptic plasticity. 
Dr. Huganir is also Associate Professor ofNeu- 
roscience and of Biological Chemistry at the fohns 
Hopkins University School of Medicine. 
Books and Chapters of Books 
Blackstone, CD., Raymond, L., Moss, S.J., and 
Huganir, R.L. 1992. Regulation of non-NMDA 
glutamate receptors by protein phosphorylation. 
In Excitatory Amino Acids (Simon, R.P., Ed.). 
New York: Thieme Medical Publishers, pp 15- 
20. 
Articles 
Blackstone, CD., Levey, A.I., Martin, L.J., Price, 
D.L., and Huganir, R.L. 1992. Immunological 
detection of glutamate receptor subtypes in hu- 
man central nervous system. Ann Neurol 31: 
680-683. 
Blackstone, CD., Moss, S.J., Martin, L.J., Levey, 
A.I., Price, D.L., and Huganir, R.L. 1992. Bio- 
chemical characterization and localization of a 
non-A^-methyl-D-aspartate glutamate receptor in 
rat hT?im. f Neurochem 58:1 118-1 126. 
Ferris, CD., Cameron, A.M., Bredt, D.S., Huganir, 
R.L., and Snyder, S.H. 1992. Autophosphorylation 
of inositol 1 ,4,5-trisphosphate receptors. / 5/o/ 
Chem 267:7036-7041. 
Ferris, CD., Cameron, A.M., Huganir, R.L., and 
Snyder, S.H. 1992. Quantal calcium release by pu- 
rified reconstituted inositol 1 ,4,5-trisphosphate 
receptors. Nature 356:350-352. 
Martin, L.J., Blackstone, CD., Huganir, R.L., and 
Price, D.L. 1992. Cellular localization of a me- 
tabotropic glutamate receptor in rat brain. Neu- 
ron 9:259-270. 
Moss, S.J., Blackstone, CD., and Huganir, R.L. 
1992. Phosphorylation of recombinant non- 
NMDA glutamate receptors on serine and tyrosine 
residues. Neurochem Res 18:105-110. 
Moss, S.J., Doherty, CA., and Huganir, R.L. 
1992. Identification of the cAMP-dependent pro- 
tein kinase and protein kinase C phosphorylation 
sites within the major intracellular domains of the 
72S, and 72L subunits of the 7-aminobutyric 
acid type A receptor. / Biol Chem 267:14470- 
14476. 
Moss, S.J., Smart, T.G., Blackstone, CD., and 
Huganir, R.L. 1992. Functional modulation of 
GABA^ receptors by cAMP-dependent protein 
phosphorylation. Science 257:661-665. 
Swope, S.L., Moss, S.J., Blackstone, CD., and Hu- 
ganir, R.L. 1992. Phosphorylation of ligand- 
gated ion channels: a possible mode of synaptic 
plasticity. FASEB / 6:25 14-2523. 
Wagner, K., Edson, K., Heginbotham, L., Post, M., 
Huganir, R.L., and Czernik, A.J. 1991. Determi- 
nation of the tyrosine phosphorylation sites of the 
nicotinic acetylcholine receptor. / Biol Chem 
266:23784-23789. 
Zeitlin, P.L., Crawford, I., Lu, L., Woel, S., Cohen, 
M.E., Donowitz, M., Montrose, M.H., Hamosh, A., 
Cutting, G.R., Gruenert, D., Huganir, R.L., Ma- 
loney. P., and Guggino, W.B. 1992. CFTR protein 
expression in primary and cultured epithelia. 
Proc Natl Acad Sci USA 89:344-347. 
MOLECULAR BASIS OF EXCITATION AND RECOVERY IN PHOTOTRANSDUCTION 
James B. Hurley, Ph.D., Associate Investigator 
Photoreceptor cells of both vertebrate and inver- 
tebrate retinas respond to light via highly sensitive 
G protein-mediated signal transduction cascades. 
Light hyperpolarizes vertebrate photoreceptors by 
stimulating hydrolysis of the intracellular second 
messenger cGMP. Light depolarizes invertebrate 
photoreceptors via production of the second mes- 
senger inositol trisphosphate. In both types of 
photoreceptor, the initial excitation phase of 
phototransduction is followed by recovery and de- 
sensitization. Dr. Hurley and his colleagues are 
studying the molecular mechanisms of photoexcita- 
tion, recovery, and adaptation. 
Vertebrate Phototransduction 
Light initiates photoreceptor excitation by iso- 
merizing the retinal chromophore of rhodopsin. 
Within the rod and cone cells of vertebrate retinas, 
photo lyzed rhodopsin stimulates transducin, a pho- 
toreceptor-specific heterotrimeric G protein. Acti- 
406 
