The Intriguing Landscape of Single‐Cell Protein Analysis

Abstract

Profiling protein expression at single‐cell resolution is essential for fundamental biological research (such as cell differentiation and tumor microenvironmental examination) and clinical precision medicine where only a limited number of primary cells are permitted. With the recent advances in engineering, chemistry, and biology, single‐cell protein analysis methods are developed rapidly, which enable high‐throughput and multiplexed protein measurements in thousands of individual cells. In combination with single cell RNA sequencing and mass spectrometry, single‐cell multi‐omics analysis can simultaneously measure multiple modalities including mRNAs, proteins, and metabolites in single cells, and obtain a more comprehensive exploration of cellular signaling processes, such as DNA modifications, chromatin accessibility, protein abundance, and gene perturbation. Here, the recent progress and applications of single‐cell protein analysis technologies in the last decade are summarized. Current limitations, challenges, and possible future directions in this field are also discussed.

Counting Protein Number in a Single Cell by a Picoliter Liquid Operating Technology

“…Single-cell sampling with a volume of tens of picoliters is the basis of the scPILOT system. However, the sample volume failed to keep constant while the single-cell sample was obtained in the conventional, negative-pressure-based way with capillary. ,, To break this barrier, we herein introduce the air-bubble adhesion method, a new single-cell sampling method based on the special character that cells tend to “stick” directly to the air bubble. As shown in Figure b and described in the experimental section above, the pre-aspirated air in the capillary functioned as “glue” to grab target cells in the single-cell suspension.…”

Optimizing medium composition with wastewater from Coffea arabica processing to produce single‐cell protein using Candida sorboxylosa

“…[16][17][18] Due to its carbohydrate, lipid, mineral, vitamin (mainly B-complex), and essential amino acid (e.g., methionine and lysine) content, the SCP obtained from various microorganisms (including yeast) can be used as an inexpensive alternative protein source for animal feed supplements. 19,20 Given their minimal energy requirements and high growth rates at room temperature, Candida spp. are the most commonly used organisms in the production of SCP.…”

“…Single‐cell protein (SCP) is defined as the dead and dried forms of microorganisms with high protein content (40%–80% of total weight) composed of several constituents 16‐18 . Due to its carbohydrate, lipid, mineral, vitamin (mainly B‐complex), and essential amino acid (e.g., methionine and lysine) content, the SCP obtained from various microorganisms (including yeast) can be used as an inexpensive alternative protein source for animal feed supplements 19,20 . Given their minimal energy requirements and high growth rates at room temperature, Candida spp.…”

Recent Advances in the Prediction of Subcellular Localization of Proteins and Related Topics

“…In the field of proteomics, equivalent studies exist. For example, the importance of single-cell proteomics is increasing because the amount of mRNAs is not enough to know the amount of their protein products ( Xie & Ding, 2022 ). However, it seems that currently the word, spatial proteomics, means subcellular proteomics, reflecting the current excitement in this field.…”