About

Wayne L. Hubbell is a Distinguished Professor Emeritus at UCLA, with a background that includes graduate and postdoctoral work at Stanford University under Harden McConnell. His early research used spin label technology to describe the fluidity and fluidity gradient in biological membranes, making landmark contributions to cell and membrane biology. He joined the faculty at UC Berkeley in 1970, where his laboratory designed new surfactants, pioneered the molecular characterization of reconstituted membrane proteins, and developed unique spin label probes to study membrane electrostatics. In 1983, Prof. Hubbell moved to UCLA, becoming the first Jules Stein Professor of Ophthalmology and Professor of Chemistry and Biochemistry. He combined advances in molecular biology and EPR spectroscopy to pioneer site-directed spin labeling (SDSL), a powerful technology for determining the structure and conformational dynamics of soluble and membrane proteins. His work in developing and applying SDSL has earned him numerous honors, including the Gold Medal of the International EPR/ESR Society, the International Zavoisky Award, and the Bruker Prize from the Royal Society of Chemistry-ESR Group. He is a member of the National Academy of Sciences, the American Academy of Arts and Sciences, and a fellow of the Biophysical Society, among other distinctions. His research focuses on understanding the relationship between protein structure, dynamics, and function, particularly in visual signal transduction proteins such as rhodopsin, transducin, and arrestin, utilizing site-directed spin labeling and electron paramagnetic resonance techniques.

Research topics

• Biotechnology
• Chemistry
• Biochemistry
• Immunology
• Pharmacology
• Biology
• Computational biology
• Bioinformatics

Selected publications

• BPS2026 – A strategy to trap the denatured state of a helical-bundle membrane protein in lipid bilayers

  Biophysical Journal · 2026-02-01

  article
  PublisherDOI

• The lipid bilayer strengthens the cooperative network of membrane proteins

  Science Advances · 2025-07-02 · 3 citations

  articleOpen access

  Membrane proteins fold and function in a lipid bilayer constituting cell membranes. Nonetheless, their structure and function can be recapitulated in diverse amphiphilic assemblies whose compositions deviate from native membranes. It remains unclear how various hydrophobic environments stabilize membrane proteins and whether lipids play any unique role in protein stability compared to other types of amphiphiles. Here, using the evolutionarily unrelated α-helical and β-barrel membrane proteins from Escherichia coli , we find that the hydrophobic thickness and the strength of amphiphile-amphiphile packing in amphiphilic assemblies are critical determinants of protein stability. Lipid solvation enhances protein stability by facilitating residue burial in the protein interior, reminiscent of the lipophobic effect. This lipid-mediated mechanism also strengthens the cooperative residue-interaction network, promoting the propagation of local structural perturbations throughout the protein. This study demonstrates the pivotal role of lipid solvation in modulating the stability of membrane proteins and their responses to external stimuli.

  PublisherDOI

• BPS2025 - The voltage-dependent anion channel is a flexible barrel

  Biophysical Journal · 2025-02-01

  article
  PublisherDOI

• Ligand efficacy modulates conformational dynamics of the µ-opioid receptor

  Nature · 2024-04-10 · 71 citations

  articleOpen access

  Abstract The µ-opioid receptor (µOR) is an important target for pain management 1 and molecular understanding of drug action on µOR will facilitate the development of better therapeutics. Here we show, using double electron–electron resonance and single-molecule fluorescence resonance energy transfer, how ligand-specific conformational changes of µOR translate into a broad range of intrinsic efficacies at the transducer level. We identify several conformations of the cytoplasmic face of the receptor that interconvert on different timescales, including a pre-activated conformation that is capable of G-protein binding, and a fully activated conformation that markedly reduces GDP affinity within the ternary complex. Interaction of β-arrestin-1 with the μOR core binding site appears less specific and occurs with much lower affinity than binding of G i .

  PublisherOA PDFDOI

• A pressure-jump EPR system to monitor millisecond conformational exchange rates of spin-labeled proteins

  bioRxiv (Cold Spring Harbor Laboratory) · 2024-05-10 · 2 citations

  preprintOpen access

  Site-directed spin labeling electron paramagnetic resonance (SDSL-EPR) using nitroxide spin labels is a well-established technology for mapping site-specific secondary and tertiary structure and for monitoring conformational changes in proteins of any degree of complexity, including membrane proteins, with high sensitivity. SDSL-EPR also provides information on protein dynamics in the time scale of ps-µs using continuous wave lineshape analysis and spin lattice relaxation time methods. However, the functionally important time domain of µs-ms, corresponding to large-scale protein motions, is inaccessible to those methods. To extend SDSL-EPR to the longer time domain, the perturbation method of pressure-jump relaxation is implemented. Here, we describe a complete high-pressure EPR system at Q-band for both static pressure and millisecond-timescale pressure-jump measurements on spin-labeled proteins. The instrument enables pressure jumps both up and down from any holding pressure, ranging from atmospheric pressure to the maximum pressure capacity of the system components (~3500 bar). To demonstrate the utility of the system, we characterize a local folding-unfolding equilibrium of T4 lysozyme. The results illustrate the ability of the system to measure thermodynamic and kinetic parameters of protein conformational exchange on the millisecond timescale.

  PublisherOA PDFDOI

• A pressure‐jump <scp>EPR</scp> system to monitor millisecond conformational exchange rates of spin‐labeled proteins

  Protein Science · 2024-11-20 · 5 citations

  articleOpen access

  Site-directed spin labeling electron paramagnetic resonance (SDSL-EPR) using nitroxide spin labels is a well-established technology for mapping site-specific secondary and tertiary structure and for monitoring conformational changes in proteins of any degree of complexity, including membrane proteins, with high sensitivity. SDSL-EPR also provides information on protein dynamics in the timescale of ps-μs using continuous wave lineshape analysis and spin lattice relaxation time methods. However, the functionally important time domain of μs-ms, corresponding to large-scale protein motions, is inaccessible to those methods. To extend SDSL-EPR to the longer time domain, the perturbation method of pressure-jump relaxation is implemented. Here, we describe a complete high-pressure EPR system at Q-band for both static pressure and ms-timescale pressure-jump measurements on spin-labeled proteins. The instrument enables pressure jumps both up and down from any holding pressure, ranging from atmospheric pressure to the maximum pressure capacity of the system components (~3500 bar). To demonstrate the utility of the system, we characterize a local folding-unfolding equilibrium of T4 lysozyme. The results illustrate the ability of the system to measure thermodynamic and kinetic parameters of protein conformational exchange on the ms timescale.

  PublisherOA PDFDOI

• A Highly Ordered Nitroxide Side Chain for Distance Mapping and Monitoring Slow Structural Fluctuations in Proteins

  Applied Magnetic Resonance · 2023-10-14 · 12 citations

  articleOpen accessSenior author

  Site-directed spin labeling electron paramagnetic resonance (SDSL-EPR) is an established tool for exploring protein structure and dynamics. Although nitroxide side chains attached to a single cysteine via a disulfide linkage are commonly employed in SDSL-EPR, their internal flexibility complicates applications to monitor slow internal motions in proteins and to structure determination by distance mapping. Moreover, the labile disulfide linkage prohibits the use of reducing agents often needed for protein stability. To enable the application of SDSL-EPR to the measurement of slow internal dynamics, new spin labels with hindered internal motion are desired. Here, we introduce a highly ordered nitroxide side chain, designated R9, attached at a single cysteine residue via a non-reducible thioether linkage. The reaction to introduce R9 is highly selective for solvent-exposed cysteine residues. Structures of R9 at two helical sites in T4 Lysozyme were determined by X-ray crystallography and the mobility in helical sequences was characterized by EPR spectral lineshape analysis, Saturation Transfer EPR, and Saturation Recovery EPR. In addition, interspin distance measurements between pairs of R9 residues are reported. Collectively, all data indicate that R9 will be useful for monitoring slow internal structural fluctuations, and applications to distance mapping via dipolar spectroscopy and relaxation enhancement methods are anticipated. Supplementary Information: The online version contains supplementary material available at 10.1007/s00723-023-01618-8.

  PublisherOA PDFDOI

• Conformational dynamics of the μ-opioid receptor determine ligand intrinsic efficacy

  bioRxiv (Cold Spring Harbor Laboratory) · 2023-04-29 · 7 citations

  preprintOpen access

  Abstract The μ-opioid receptor (μOR) is an important target for pain management and the molecular understanding of drug action will facilitate the development of better therapeutics. Here we show, using double electron-electron resonance (DEER) and single-molecule fluorescence resonance energy transfer (smFRET), how ligand-specific conformational changes of the μOR translate into a broad range of intrinsic efficacies at the transducer level. We identify several cytoplasmic receptor conformations interconverting on different timescales, including a pre-activated receptor conformation which is capable of G protein binding, and a fully activated conformation which dramatically lowers GDP affinity within the ternary complex. Interaction of β-arrestin-1 with the μOR core binding site appears less specific and occurs with much lower affinity than binding of G protein G i . One-Sentence Summary Ligand-dependent conformational dynamics of the μ-opioid receptor determine downstream signaling efficacy.

  PublisherOA PDFDOI

• Membrane potential accelerates sugar uptake by stabilizing the outward facing conformation of the Na/glucose symporter vSGLT

  Nature Communications · 2023-11-18 · 12 citations

  articleOpen access

  ion gradient to actively transport sugars. Here, we investigate the impact of the membrane potential on vSGLT structure and function using sugar uptake assays, double electron-electron resonance (DEER), electrostatic calculations, and kinetic modeling. Negative membrane potentials, as present in all cell types, shift the conformational equilibrium of vSGLT towards an outward-facing conformation, leading to increased sugar transport rates. Electrostatic calculations identify gating charge residues responsible for this conformational shift that when mutated reduce galactose transport and eliminate the response of vSGLT to potential. Based on these findings, we propose a comprehensive framework for sugar transport via vSGLT, where the cellular membrane potential facilitates resetting of the transporter after cargo release. This framework holds significance not only for SGLTs but also for other transporters and channels.

  PublisherOA PDFDOI

• Conformational flexibility of HIV-1 envelope glycoproteins modulates transmitted / founder sensitivity to broadly neutralizing antibodies

  bioRxiv (Cold Spring Harbor Laboratory) · 2023-09-13 · 5 citations

  preprintOpen access

  Abstract HIV-1 envelope glycoproteins (Envs) mediate viral entry and are the sole target of neutralizing antibodies. Envs of most primary HIV-1 strains exist in a closed conformation and occasionally sample more open states. Thus, current knowledge guides immunogen design to mimic the closed Env conformation as the preferred target for eliciting broadly neutralizing antibodies (bnAbs) to block HIV-1 entry. Here we show that Env-preferred conformations of 6 out of 13 (46%) transmitted/founder (T/F) strains tested are incompletely closed. As a result, entry of these T/Fs into target cells is sensitive to antibodies that recognize internal epitopes exposed on open Env conformations. A cryo-electron microscopy structure of unliganded, incompletely closed T/F Envs (1059-SOSIP) at 3.6 Å resolution exhibits an asymmetric configuration of Env protomers with increased sampling of states with incompletely closed trimer apex. Double electron-electron resonance spectroscopy provided further evidence for enriched occupancy of more open Env conformations. Consistent with conformational flexibility, 1059 Envs were associated with resistance to most bnAbs that exhibit reduced potency against functional Env intermediates. To follow the fate of incompletely closed Env in patients, we reconstructed de novo the post-transmission evolutionary pathway of a second T/F Env (CH040), which is sensitive to the V3-targeting antibody 19b and highly resistant to most bnAbs. Evolved viruses exhibited increased resistance to cold, soluble CD4 and 19b, all of which correlate with closing of the adapted Env trimer. Lastly, we show a correlation between efficient neutralization of multiple Env conformations and increased antiviral breadth of CD4-binding site (CD4bs) bnAbs. In particular, N6 bnAb, which uniquely recognizes different Env conformations, efficiently neutralizes 50% of the HIV-1 strains that were resistant to VRC01 and transmitted during the first-in-humans antibody-mediated prevention trial (HVTN 704). VRC01-resistant Envs are incompletely closed based on their sensitivity to cold and on partial sensitivity to antibodies targeting internal, typically occluded, epitopes. Most VRC01-resistant Envs retain the VRC01 epitope according to VRC01 binding to their gp120 subunit at concentrations that have no significant effect on virus entry, and they exhibit cross resistance to other CD4bs bnAbs that poorly recognize functional Env intermediates. Our findings refine current knowledge of Env conformational states and provide guidance for developing new strategies for bnAb immunotherapy and Env-based immunogen design.

  PublisherOA PDFDOI

Recent grants

• Molecular Basis of Membrane Excitation

  NIH · $10.6M · 1983–2020

• Prototype Construction Core

  NIH · $16.4M · 1997–2029

• NIH Grant R37EY005216

  NIH · $2.8M · 2000

Frequent coauthors

• Christian Altenbach

  University of California, Los Angeles

  241 shared

• Kálmán Hideg

  92 shared

• Ned Van Eps

  76 shared

• H. Ronald Kaback

  65 shared

• Zhongyu Yang

  North Dakota State University

  59 shared

• Michael D. Bridges

  Doheny Eye Institute

  59 shared

• Vsevolod V. Gurevich

  Vanderbilt University

  55 shared

• John C. Voss

  University of California, Davis

  46 shared

Awards & honors

• Gold Medal of the International EPR/ESR Society
• International Zavoisky Award from the Physical Technical Ins…
• Bruker Prize from the Royal Society of Chemistry-ESR Group
• Elisabeth Roberts Cole Award from the Biophysical Society (U…
• Fellow of the National Academy of Sciences