Lan Guan, M.D. Ph.D. | Texas Tech University Health Sciences Center

Professor | Cell Physiology and Molecular Biophysics

Co-Director | Center for Membrane Protein Research

lan guan

3601 4th Street, STOP 6551
Lubbock, Texas 79430
Office Phone: (806) 743-3102
Office Room: 5A148A

Research Interest:

Membrane proteins constitute ~30% of all eukaryotic proteins and play crucial roles in many aspects of cell function. The long-term goal of our research is to understand the mechanisms of solute transport and lay the foundation for advances in deseas treat and human health. We focusing one cation-coupled bacterial and human transporters by an integrated approach including cryo-EM single-particle analysis, X-ray crystallography, ligand binding, molecular dynamics simulations, thermodynamics, genetic engineering, novel amphiphiles, and many other biochemical & biophysical analyses.

Current Support:


2024 & Other Selected Articles:


Hariharan, P.*,  Bakhtiiari, A.*,  Liang, R.,  and Guan, L. (2024) Distinct roles of the major binding residues in the cation-binding pocket of the melibiose transporter MelB. J Biol Chem


Hariharan, P., Shi, Y., Katsube, S., Willibal, K., Burrows, N. D., Mitchell, P., Bakhtiiari, A., Stanfield, S., Pardon, E., Kaback, H. R., Liang, R., Steyaert, J., Viner, R., and Guan, L. (2024) Mobile barrier mechanisms for Na+-coupled symport in an MFS sugar transporter. eLife. 12:92462.  DOI: Open access 

  Selected Publications in the Past Years

Katsube, S., Willibal, K., Vemulapally, S., Hariharan, P., Tikhonova, E.,  Pardon, E., Kaback, H. R., Steyaert, J., and Guan, L. (2023) In vivo and in vitro characterizations of melibiose permease (MelB) conformation- dependent nanobodies reveal sugar-binding mechanisms, J Biol Chem 299:104967. DOI:

JBC Cover Oct 2023; 299 (10)

  Blaimschein, N., Hariharan, P., Manioglu, S., Guan, L., & Muller, D. J. (2023) Substrate-binding guides individual melibiose permeases MelB to structurally soften and to destabilize cytoplasmic middle-loop C3. Structure, 31(1), 58-67 e54. 
  Chua, G. L., Tan, B. C., Loke, R. Y. J., He, M., Chin, C. F., Wong, B. H., Kuk, A. C. Y., Ding, M., Wenk, M. R., Guan, L., Torta, F., and Silver, D. L. (2023) Mfsd2a utilizes a flippase mechanism to mediate omega-3 fatty acid lysolipid transport. Proc Natl Acad Sci U S A 120(10):e2215290120. doi: 10.1073/pnas.2215290120.
  Panda, A., Giska, F., Duncan, A. L., Welch, A. J., Brown, C., McAllister, R., Hariharan, P., Goder, J. N. D., Coleman, J., Ramakrishnan, S., Pincet, F.,  Guan, L.,  Krishnakumar, S., Rothman, J. E., and Gupta, K (2023) Direct determination of oligomeric organization of integral membrane proteins and lipids from intact customizable bilayer', Nature Methods, 20: 891-97.
  Guan, L. (2022) Editorial,  Structure and mechanism of membrane transporters. Scientific Reports 12:13248
  Katsube, S., Liang, R., Amin, A., Hariharan, P., & Guan, L. (2022). Molecular Basis for the Cation Selectivity of Salmonella typhimurium Melibiose Permease. Journal of Molecular Biology, 434(12), 167598. 
  Guan, L., Hariharan, P. (2021) X-ray crystallography reveals molecular recognition mechanism for sugar binding in a melibiose transporter MelB. Commun Biol 4, 931.
  Guan, L. (2020) Glucose/Sugar Transport in Bacteria. Encyclopedia of Biochemistry, 3rd edition, Elsevier Inc. Published in the Life Sciences Reference Collection
  H. Ronald Kaback and Lan Guan. (2019)  It takes two to tango: the dance of the permease. J Gen Physiol. 151(7):878-886. doi: 10.1085/jgp.201912377.
  Hariharan, P., Tikhonova, E., Medeiros-Silva, J., Jeucken, A., Bogdanov, M.V., Dowhan, W., Brouwers, J. F., Weingarth, M. and Guan, L. (2018) Structural and functional characterization of protein–lipid interactions of the Salmonella typhimurium melibiose transporter MelB. BMC Biology 16:85 doi: 10.1186/s12915-018-0553-0
  Guan, L. (2018) Na(+)/Melibiose Membrane Transport Protein, MelB. In: Roberts G., Watts A., European Biophysical Societies (eds) Encyclopedia of Biophysics. Springer. DOI: 10.1007/978-3-642-35943-9_10082-1
ncbi Hariharan, P. & Guan. L. (2017) Thermodynamic cooperativity of cosubstrate binding and cation selectivity of Salmonella typhimurium MelB. J Gen Physiol. (On the Cover and Highlighted by Research News, “A symporter’s secrets shown”). DOI: 10.1085/jgp.201711922. 149(11):1029-1039. DOI: 10.1085/jgp.201711788.
ncbi Ethayathulla, A.S., Yousef, M.S., Amin, A., Leblanc, G., Kaback, H.R., and Guan, L. (2014) Structure-based mechanism for Na(+)/melibiose symport by MelB. Nature Communications. 5: 3009. DOI:10.1038/ncomms4009.
ncbi Chae, P.S., Rasmussen S.G.F., Rana, R., Gotfryd, K., Chandra, R., Goren, M.A., Kruse, A.C., Nurva, S., Loland, J.C., Pierre, Y., Drew, D., Popot, J.L., Picot, D., Fox, B.G., Guan, L., Gether, U., Byrne, B., Kobilka, B., and Gellman, S.H. (2010) Maltose–neopentyl glycol (MNG) amphiphiles for solubilization, stabilization, and crystallization of membrane proteins. Nature Methods.  7(12):1003-1008. DOI: 10.1038/nmeth.1526.
ncbi Guan, L., Mirza, O., Verner, G., Iwata, S, and Kaback, H.R. (2007) Structural determination of the wild-type lactose permease. Proc Natl Acad Sci U S A, 104 (39):15294-15298. DOI: 10.1073/pnas.0707688104.
ncbi Guan, L. & Kaback, H.R. (2007) Site-directed alkylation of cysteine to test solvent accessibility of membrane proteins. Nature Protocols. 2(28), 2012-2017. DOI: 10.1038/nprot.2007.275.
ncbi Guan, L. & Kaback, H.R. (2006) Lessons from lactose permease. Annual Review of Biophysics & Biomolecular Structure. (35):67-91.DOI: 10.1146/annurev.biophys.35.040405.102005.

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Lan Guan, M.D. Ph.D.