Prevalence of alternative first exons in various functional gene classes
Gene category . | Total no. genes . | No. genes with alternative first exons . | Genes with alternative first exons, % . |
|---|---|---|---|
| Globins | 9 | 0 | 0.0 |
| Heme biosynthesis | 8 | 3 | 37.5 |
| Transcription factors | 11 | 6 | 54.5 |
| Cytoskeletal proteins | 13 | 7 | 53.8 |
| Plasma membrane proteins | 33 | 10 | 30.3 |
| Glycolytic enzymes etc | 29 | 10 | 34.5 |
Gene category . | Total no. genes . | No. genes with alternative first exons . | Genes with alternative first exons, % . |
|---|---|---|---|
| Globins | 9 | 0 | 0.0 |
| Heme biosynthesis | 8 | 3 | 37.5 |
| Transcription factors | 11 | 6 | 54.5 |
| Cytoskeletal proteins | 13 | 7 | 53.8 |
| Plasma membrane proteins | 33 | 10 | 30.3 |
| Glycolytic enzymes etc | 29 | 10 | 34.5 |
We compared the prevalence of genes with alternative first exons among the various gene groups analyzed in this study. Certain categories appear more likely to exhibit alternative first exons. For example, none of the globin genes possess alternative 5′ ends, whereas more than half of the erythroid transcription factors and cytoskeletal proteins display such feature. The data suggest that 5′ complexity may represent an important genetic mechanism for certain cellular processes.