| GO:0005506 | iron ion binding | 51 |
| GO:0016597 | amino acid binding | 49 |
| GO:0009072 | aromatic amino acid family metabolic process | 29 |
| GO:0004510 | tryptophan 5-monooxygenase activity | 24 |
| GO:0004505 | phenylalanine 4-monooxygenase activity | 23 |
| GO:0042427 | serotonin biosynthetic process | 22 |
| GO:0006559 | L-phenylalanine catabolic process | 22 |
| GO:0016714 | oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced pteridine as one donor, and incorporation of one atom of oxygen | 7 |
| GO:0045187 | regulation of circadian sleep/wake cycle, sleep | 1 |
| GO:0007616 | long-term memory | 1 |
| GO:0005811 | lipid particle | 1 |
| GO:0006909 | phagocytosis | 1 |
