9PN1

Crystal structure of Q108K:K40L:T51V:T53C:R58W:T29L:Y19W:Q4A mutant of cellular retinol binding protein II complex with 15-cis-retinal

Replaces:  7LHJ

Summary for 9PN1

• Entry DOI: 10.2210/pdb9pn1/pdb
• Descriptor: Retinol-binding protein 2, ACETATE ION, RETINAL, ... (5 entities in total)
• Functional Keywords: hcrbpii, q4a, isomerization, retinal, cis, trans, rhodopsin, bacteriorhodopsin, cytosolic protein, transport protein
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 2
• Total formula weight: 31958.26

Authors

Ehyaei, N.,Silva, K.,Bingham, C.,Geiger, J.H.,Borhan, B. (deposition date: 2025-07-18, release date: 2026-06-10)

Primary citation

Ehyaei, N.,Bingham, C.,Silva, K.,Nossoni, Z.,Gavgani, H.N.,Nosrati, M.,Eaves, J.,Akhdar, M.,Vasileiou, C.,Borhan, B.,Geiger, J.H.
Photoisomerization detected in a fully wavelength-tunable rhodopsin mimic system.
Acta Crystallogr D Struct Biol, 82:664-671, 2026

PubMed Abstract: We describe the photoisomerization of the retinylidene protonated Schiff base in human retinol-binding protein II (hCRBPII) and the role of water molecules in this process. We characterize the photoisomerization of the 15-cis/all-trans retinylidene protonated Schiff base in this system using UV-visible spectroscopy and atomic-resolution X-ray crystallography. We further demonstrate a process where the pK of the protonated Schiff base is substantially altered by light-induced dehydration of the binding pocket, suggesting novel pathways of photoswitching that rely not on isomerization or conformational change of the chromophore but rather on light-induced reorganization of the protein environment.

PubMed: 42201784
DOI: 10.1107/S2059798326003839

Experimental method

X-RAY DIFFRACTION (1.26 Å)