Nukleiinhapetes

Nukleiinhapetes, also known as nucleoside diphosphate kinase (NDPK), is a family of enzymes involved in the transfer of phosphate groups between nucleoside di- and tri-phosphates. These enzymes play a critical role in cellular energy metabolism and signal transduction pathways. The name "nukleiinhapetes" is derived from the Greek words *nucleos* (nucleus) and *hapetes* (to bind), reflecting their function in phosphate transfer within nucleotide metabolism.

NDPK enzymes are widely distributed across all domains of life, including bacteria, archaea, and eukaryotes. In humans, there are four known isoforms (NM23-H1 to NM23-H4), with NM23-H1 being the most studied. These enzymes are small, dimeric proteins that catalyze the reaction:

Nucleoside diphosphate + Nucleoside triphosphate ↔ Nucleoside triphosphate + Nucleoside diphosphate

This reaction helps maintain the balance of nucleotide pools, which is essential for DNA replication, RNA synthesis, and other cellular processes. Beyond their metabolic role, NDPKs have been implicated in various cellular functions, including cell proliferation, differentiation, and apoptosis.

The NM23 family of NDPKs, particularly NM23-H1, has gained attention due to its potential role in cancer metastasis. Studies suggest that reduced expression of NM23-H1 is associated with increased metastatic potential in certain cancers, though the exact mechanisms remain under investigation. Additionally, NDPKs have been linked to other diseases, such as neurodegenerative disorders and viral infections, where their activity may influence disease progression.

Structurally, NDPKs share a conserved core domain with a characteristic phosphate-binding loop. Their activity is regulated by various factors, including post-translational modifications, interactions with other proteins, and cellular localization. Research into NDPKs continues to explore their broader physiological roles and potential as therapeutic targets.