Dataset Information

2018CHPP

ABSTRACT: ABSTRACT Since 2012, Chromosome-Centric Human Proteome Project (C-HPP) launched the journey of missing proteins (MPs) investigation for completing human proteome project (HPP). We found the majority of MPs were distributed in low molecular weight (LMW) ranges, especially in 0-40 kDa. The identification of LMW proteins is challenging owing to their low length, low abundancy, and hydrophobicity. Even worse, many sequences from Trypsin digestion are unlikely to yield detectable peptides or composed less number of observable peptides in MS detection. Therefore, we focused on small MPs by combining LMW protein enrichment and mirror-protease strategy on human testis samples. The in-depth testis LMW protein profiling documented 4,063 proteins from which 2,565 proteins were belong to LMW proteins and 1,130 proteins had mirror peptides. This provided mass spectral evidence for small MPs further verification, and two MPs were verified in seven identified MPs. For Q8N688, confident peptides were verified from Trypsin and LysargiNase digestions, and continuous b/y-ion peptide was obtained by mirror-spectrum matching. Two verified peptides of Q86WR6 were from gel-separation and gel-elution dataset, respectively. And the other 5 MPs cannot be distinguished sufficiently as PE1, but need more verification information.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (ncbitaxon:9606)

SUBMITTER: Ping Xu

PROVIDER: MSV000083978 | MassIVE | Fri Jun 14 11:46:00 BST 2019

SECONDARY ACCESSION(S): PXD010093

REPOSITORIES: MassIVE

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Publications

Digging for Missing Proteins Using Low-Molecular-Weight Protein Enrichment and a "Mirror Protease" Strategy.

He Cuitong C Sun Jinshuai J Shi Jiahui J Wang Yihao Y Zhao Jialing J Wu Shujia S Chang Lei L Gao Huiying H Liu Fengsong F Lv Zhitang Z He Fuchu F Zhang Yao Y Xu Ping P

Journal of proteome research 20181016 12

In 2012, the Chromosome-centric Human Proteome Project (C-HPP) launched an investigation for missing proteins (MPs) to complete the Human Proteome Project (HPP). The majority of the MPs were distributed in low-molecular-weight (LMW) ranges, especially from 0 to 40 kDa. LMW protein identification is challenging, owing to their short length, low abundance, and hydrophobicity. Furthermore, many sequences from trypsin digestion are unlikely to yield detectable peptides or a reasonable quality of MS< ...[more]

PMID: 30277781

Similar Datasets

Project description:In recent years, high-throughput technologies have contributed to development a more precise picture of the human proteome. However, 2,129 proteins remain listed as missing proteins (MPs) in the newest neXtProt release (2019-02). The main reasons for MPs are a low abundance, low-molecular-weight (LMW), unexpected modifications, membrane characteristics, etc. Moreover, more than 50% of the MS/MS data have not been successfully identified in shotgun proteomics. Open-pFind, an efficient open search engine, recently released by the pFind group in China, presents an opportunity to identify these buried MPs in complex samples. Proteins and potential MPs were identified using Open-pFind and three other search engines to compare their performance and efficiency with three large-scale datasets digested by different enzymes. Our results demonstrated that Open-pFind identified 29.9-47.5% more peptide-spectrum matches (PSMs), 48.0-63.9% more peptides sequences (with modifications) and 22.7-38.1% more peptide sequences (regardless of modifications) than those identified by the second-best search engine. As a result, Open-pFind detected 7.5-19.3% more candidate MPs than those by the second-best search engine. In total, 5 (PE2) of the 150 candidate MPs identified by Open-pFind were verified from two unique peptides containing more than 9 amino acids (AA) by using spectrum theoretical prediction with pDeep, and synthesized peptide matching with pBuild, after spectrum quality analysis, isobaric post-translational modification, and single amino acid variant (SAAV) filtering. These five verified MPs can be ranked in the PE1 level. In addition, three other candidate MPs were verified with two unique peptides (one peptide containing more than 9 AA) and the other containing only 8 AA), which were slightly lower than the criteria listed by C-HPP, and required additional verification information. More importantly, unexpected modifications were detected in these MPs. Another 141 MPs were listed as candidates, but required additional verification information.