Cell Surface Proteomics

What is Cell Surface Proteins?

The cell-surface proteins (CSPs) are a group of proteins that traverse or are anchored/embedded in the plasma membrane, playing a crucial role in various essential and distinct cellular functions along the plasma membrane, which mediates intercellular communication and regulating cellular interactions with the extracellular milieu, including nutrient and ion transportation, intercellular interactions, receptor-mediated signaling transduction, enzymatic reactions, and immune recognition. According to Almen et al., they classified CSPs into four categories: (i) transporters, including channels, solute carriers, and active transporters; (ii) receptors, such as G protein-coupled receptors, receptor type tyrosine kinases, receptors of the immunoglobulin superfamily and related, and scavenger receptors and related; (iii) enzymes, which include oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases; and (iv) miscellaneous, such as ligands, other proteins, structural/adhesion proteins and proteins of unknown function. Due to their critical biological function and unique subcellular location, CSPs have been proposed as valuable resource for the identification of targets in immune and targeted therapy. Additionally, they have been served as informative biomarkers for assays related to early disease detection, diagnosis, and prediction. Therefore, it is essential to employ cell surface proteomics strategies for identifying and quantifying the complete repertoire of CSPs, as well as investigating their functional roles.

Our Cell Surface Proteomics Service

With advancements in quantitative proteomics and shotgun proteomics based on LC-MS/MS analysis, it is now capable of characterizing and quantifying complex protein mixtures with high throughput, exclusive accuracy, and specificity. The initial step in studying CSPs involves the isolation of these proteins from the whole cells. Various strategies can be employed for the enrichment of CSPs, including (i) differential centrifugation, (ii) density gradient centrifugation, (iii) affinity-based enrichment methods such as streptavidin-biotinylation, antibody-antigen, and lectin-glycan, and (iv) hydrazide chemistry. Combining centrifugation with affinity or chemical enrichment techniques is a favorable approach to effectively remove abundant cytosolic proteins and enhance selectivity towards CSPs. The second critical step is to dissolve the CSPs, usually using agents such as detergents (SDS, RapiGest, etc.), denaturants (Urea, etc.), extreme pH (Na₂CO₃, etc.), high ionic strength (KCl, NaCl, etc.), organics (CH₃OH, CHCl₃, etc.) to dissolution CSPs. The proteomics technology is undoubtedly the most crucial step for deep and accurate identification and quantification of CSPs. The field of quantitative proteomics has witnessed the establishment of various well-established techniques, including SILAC, iTRAQ/TMT, label-free, DIA and target quantification proteomics such as (SRM/MRM, PRM). Most importantly, the methods mentioned above have been thoroughly mastered by Creative Proteomics. With over a decade of experience in the field of proteomics, we possess exceptional proficiency in executing Cell Surface Proteomics Projects. We are capable of supporting diverse sample types and can even assist in cell culturing for SILAC quantitative proteomics.

Figure 1. Biotinylation enrichment methods for cell surface proteomics ^[3].

Technologies platform

1. Professional detection and analysis capability: Experienced technical team, strict quality control system, together with ultra-high resolution detection system and professional data pre-processing and analysis capability, ensure reliable and accurate data.
2. High specificity and purification: Optimization of experimental design and methods.
3. High stability and reproducible: Obtain consistent and reproducible inter- and intra- assay results for data analysis.
4. High throughput: LC-MS/MS can identify and quantify thousands of proteins simultaneously.
5. High resolution and sensitivity: Triple TOF 5600, Q-Exactive, Q-Exactive HF, Orbitrap Fusion™ Tribrid™, etc.
6. High selectivity: We can provide a wide range of multi-technological services and efficiently handle various types of samples, while remaining cost-effective and ensuring short turnaround times for your projects.

Results Delivery

1. Detailed report, including experiment procedures, parameters, etc.
2. Raw data and data analysis results (e.g. identified proteins and peptides, and optional downstream bioinformatics analysis, such as volcano plot, PCA, GO, KEGG, Protein Interaction Networks, etc.)

Samples Requirement

Tissue: animal tissue > 50 mg;

fresh plant > 100 mg;

Cell: suspension cell > 1 x 10⁷;

adherent cell > 1 x 10⁷;

microorganism > 50 mg or 1 x 10⁷ cells;

Body fluid: Serum/plasma > 500 μL;

Protein: Total protein >1 mg and concentration >1 μg/μL.

Note: If you provide proteins solution, please inform us of the buffer components. In addition, the sample should not contain components such as nucleic acids, lipids, and polysaccharides, and it should also not contain detergents or denaturants.

How to place an order

The provision of comprehensive support tailored to your specific requirements for Cell Surface Proteomics is our area of expertise. Please feel free to contact us via email whenever you need to discuss your specific requirements. Our customer service representatives are available 24 hours a day, from Monday to Sunday.

References

1. Almén MS, Nordström KJ, Fredriksson R, et al. Mapping the human membrane proteome: a majority of the human membrane proteins can be classified according to function and evolutionary origin. BMC Biol. 2009 Aug 13;7:50.
2. Sun B. Proteomics and glycoproteomics of pluripotent stem-cell surface proteins. Proteomics. 2015 Mar;15(5-6):1152-63.
3. Kalxdorf M, Gade S, Eberl HC, et al. Monitoring Cell-surface N-Glycoproteome Dynamics by Quantitative Proteomics Reveals Mechanistic Insights into Macrophage Differentiation. Molecular Cell Proteomics. 2017 May;16(5):770-785.

Cell-Surface Proteomics Identifies Differences in Signaling and Adhesion

Protein Expression between Naive and Primed Human Pluripotent Stem Cells

Journal: Stem Cell Reports

Published: 2020

Main technologies: Cell Surface Proteomics, TMT quantitative proteomics, Cell proliferation assay, Flow cytometry, Immunofluorescence microscopy, Western Blot, Quantitative RT-PCR

Abstract

Naive and primed human pluripotent stem cells (hPSC) provide valuable models to study cellular and molecular developmental processes. The lack of detailed information about cell-surface protein expression in these two pluripotent cell types prevents an understanding of how the cells communicate and interact with their microenvironments. Here, we used plasma membrane profiling to directly measure cell-surface protein expression in naive and primed hPSC. This unbiased approach quantified 1,715 plasma membrane proteins (74% specificity), including those involved in cell adhesion, signaling, and cell interactions. Notably, multiple cytokine receptors upstream of JAK-STAT signaling were more abundant in naive hPSC. In addition, functional experiments showed that FOLR1 and SUSD2 proteins are highly expressed at the cell surface in naive hPSC but are not required to establish human naive pluripotency. This study provides a comprehensive stem cell proteomic resource that uncovers differences in signaling pathway activity and has identified new markers to define human pluripotent states.

Figure 1. Cell-Surface Proteomics of Naive and Primed Human Pluripotent Stem Cells.