Seminar by Dr. Yong Ju Kim (Chonbuk National University) @ C015

Seminar

Title:

The understanding of visual signal transduction from X-ray structure analysis of a protein.

Speaker:

Dr. Yong Ju Kim

Chonbuk National University, Jeonju, Republic of Korea

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Date:  Tuesday, February 4^th, 2014

Time:  11:00 – 12:00 (Noon)

Venue:           C015, Lab 1, Level C

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Abstract:

The photoreceptor rhodopsin couples to transducin and bears its ligand 11-cis-retinal covalently bound via a protonated Schiff base to the opsin apoprotein. Absorption of a photon causes retinal cis/trans isomerization and generates the agonist all-trans-retinal in situ. The retinal is in a relaxed conformation and almost undistorted compared with pure crystalline all-trans-retinal. By comparison with early photoproducts we propose how retinal translocation and rotation induce the gross conformational changes characteristic for Meta II. Arrestins interact with GPCRs to block interaction with G proteins. The p44 protein is a splice variant mutant of arrestin lacking the last 35 residues of the C-tail. The structure of the pre-activated arrestin, p44 is profoundly different from the basal state and gives insight into the activation mechanism. p44 displays breakage of the central polar core and other interlobe hydrogen-bond networks, leading to a ∼21° rotation of the two lobes as compared to basal arrestin-1.

Molecular Cryo-Electron Microscopy Unit (Wolf Unit)