Joseph A. Loo

1 (310) 794-7023

Laboratory Address:
Mol Sci Bldg 1424
Paul Boyer Hall 416

Lab Number:
1 (310) 794-7308
1 (310) 825-8101

Work Address:
Paul Boyer Hall 402

Fax Number:
(310) 206-4038


Professor, Chemistry and Biochemistry, Biochemistry, Molecular Biology, Biological Chemistry
Member, Biochemistry, Biophysics & Structural Biology GPB Home Area, Molecular Biology Institute, UCLA-DOE Institute for Genomics & Proteomics
Researcher, Biochemistry, Chemical Biology, Proteomics and Bioinformatics

Research Interests

Our research focuses on the development of novel bioanalytical tools based on mass spectrometry approaches and their application for the structural characterization of proteins and their post-translational modifications, proteomics, and for biomedical research. Using electrospray ionization mass spectrometry (ESI-MS), we study large noncovalently-bound macromolecular complexes and their interactions with inhibitors and important ligands. ESI-MS is used to characterize the quaternary structure of important protein complexes and to identify biologically relevant protein-ligand complexes. MS-based methods are being developed for characterizing protein-protein interface interactions to be used as a predicative tool for the bonding characteristics of the interactions. Mass spectrometry sequencing methods can pinpoint ligand binding sites, for example, nucleotide binding sites to protein kinases. Novel methods for isolating and identifying important protein complexes, or machines, will depend on the high sensitivity of bioanalytical mass spectrometry. Proteome mapping of important organisms can form the framework for future studies aimed at elucidating biochemical pathways. Monitoring protein expression of causative infectious agents in the presence of potential drugs and their comparison with a reference profile can be used to determine mechanism of action and identify potential protein targets for drug discovery.


Dr. Joseph A. Loo is a Professor in the Department of Biological Chemistry, David Geffen School of Medicine, and in the Department of Chemistry & Biochemistry at the University of California, Los Angeles (UCLA), and he is the Faculty Director of the UCLA Mass Spectrometry and Proteomics Technology Center. He is also a member of UCLA/DOE Laboratory for Genomics and Proteomics, the UCLA Molecular Biology Institute, and the UCLA Jonsson Comprehensive Cancer Center. He is an expert in the mass spectrometry characterization of proteins and their post-translational modifications, and is the author of over 180 scientific publications. In 2000-2002, he served on the Board of Directors for the American Society for Mass Spectrometry. He has been on the Editorial Boards of the journals Bioconjugate Chemistry, Analytical Chemistry, Journal of the American Society for Mass Spectrometry (JASMS), and Chemical & Engineering News and currently he serves on the Editorial Advisory Board for Rapid Communications in Mass Spectrometry and as an Associate Editor for JASMS. His research interests include the development of bioanalytical methods for the structural characterization of proteins and their application for proteomics and disease biomarkers. He was one of the first researchers to apply electrospray ionization mass spectrometry (ESI-MS) to directly measure noncovalently-bound macromolecular assemblies and their interactions with other binding partners and ligands. The method can be applied to measure drug binding to their targeted proteins to even larger complexes in excess of 1 MDa. Currently, his laboratory is developing technologies to profile proteins in human salivary fluids for their application for human disease biomarker discovery. He co-authored a study with a consortium composed of groups from UCLA, UCSF, and Scripps that details the first catalog and preliminary analysis of ductal salivary proteins. In 2008, he received one of the first grants made under the new “Exceptional, Unconventional Research Enabling Knowledge Acceleration (EUREKA)” NIH program. The goal of this program is to “help investigators test novel, often unconventional hypotheses or tackle major methodological or technical challenges”. The Loo award is to study the “Impact of Non-Canonical Decoding on the Proteome”. Before he joined UCLA in 2001, he was Group Leader of the Biological Mass Spectrometry and Proteomics Teams at Warner-Lambert/Parke-Davis Pharmaceutical (currently Pfizer Global Research). He worked at Parke-Davis/Pfizer for nearly 10 years before moving to UCLA.


A selected list of publications: