How can proteomics identify differences between the number of protein-coding genes predicted for a genome and the number of proteins expressed by a genome?

Verified step by step guidance

1. Understand that proteomics is the large-scale study of proteins, particularly their structures and functions, and it directly measures proteins expressed in a cell or tissue under specific conditions.
2. Recognize that the number of protein-coding genes predicted for a genome is based on genomic DNA sequence analysis and gene annotation, which estimates potential proteins that could be produced.
3. Use proteomics techniques, such as mass spectrometry, to experimentally identify and quantify the proteins actually expressed in the sample, providing empirical data on protein presence.
4. Compare the list of proteins detected by proteomics with the predicted protein-coding genes from the genome to identify which predicted genes are expressed as proteins and which are not detected under the tested conditions.
5. Analyze discrepancies to understand biological factors such as gene regulation, alternative splicing, post-translational modifications, or technical limitations that may explain differences between predicted genes and observed proteins.

Key Concepts

Proteomics

Proteomics is the large-scale study of proteins, focusing on their structures, functions, and expression levels. It uses techniques like mass spectrometry to identify and quantify proteins expressed in a cell or organism, providing direct evidence of protein presence beyond gene predictions.

Protein-Coding Genes vs. Protein Expression

Protein-coding genes are DNA sequences predicted to produce proteins, but not all genes are expressed at all times or in all tissues. Protein expression depends on regulatory mechanisms, so the actual number of proteins detected can differ from the number of predicted genes.

Gene Expression Regulation and Post-Transcriptional Modifications

Gene expression is regulated at multiple levels, including transcription, RNA processing, and translation. Post-transcriptional modifications and alternative splicing can alter protein products, causing discrepancies between gene predictions and proteins detected by proteomics.