Question

Annotation of human genome sequence reveals that our genome contains 30000- 33000 genes. Proteomic analysis indicates that human cells are capable of synthesizing more than 30,000 different proteins. How can this discrepancy be reconciled?

Answer 1

The discrepancy between the number of genes and the number of proteins in humans can be explained by alternative splicing and post-translational modifications of proteins.

Alternative splicing is a process in which different mRNA transcripts are generated from a single gene, leading to the production of different protein isoforms. This allows for a greater diversity of proteins to be produced from a limited number of genes.

Post-translational modifications, such as phosphorylation, acetylation, and glycosylation, can also modify the structure and function of proteins, leading to even more diversity in protein function.

In addition, the number of proteins synthesized by human cells can also be influenced by factors such as environmental conditions and cell type. Thus, the number of proteins synthesized by human cells may be greater than the number of genes due to the intricate regulation of gene expression and protein synthesis.