Tissue-Based Proteogenomics Reveals that Human Testis Endows Plentiful Missing Proteins

Investigations
of missing proteins (MPs) are being endorsed by
many bioanalytical strategies. We proposed that proteogenomics of
testis tissue was a feasible approach to identify more MPs because
testis tissues have higher gene expression levels. Here we combined
proteomics and transcriptomics to survey gene expression in human
testis tissues from three post-mortem individuals. Proteins were extracted
and separated with glycine- and tricine-SDS-PAGE. A total of 9597
protein groups were identified; of these, 166 protein groups were
listed as MPs, including 138 groups (83.1%) with transcriptional evidence.
A total of 2948 proteins are designated as MPs, and 5.6% of these
were identified in this study. The high incidence of MPs in testis
tissue indicates that this is a rich resource for MPs. Functional
category analysis revealed that the biological processes that testis
MPs are mainly involved in are sexual reproduction and spermatogenesis.
Some of the MPs are potentially involved in tumorgenesis in other
tissues. Therefore, this proteogenomics analysis of individual testis
tissues provides convincing evidence of the discovery of MPs. All
mass spectrometry data from this study have been deposited in the
ProteomeXchange (data set identifier PXD002179).