inositol tetrakisphosphate 6-kinase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: 1D-myo-inositol 1,3,4,5-tetrakisphosphate + ATP = 1D-myo-inositol 1,3,4,5,6-pentakisphosphate + ADP. [GOC:elh]

Inositol tetrakisphosphate 6-kinase (IP4K) activity is a crucial enzymatic function responsible for the phosphorylation of inositol tetrakisphosphate (IP4) at the 6-position, generating inositol pentakisphosphate (IP5). This reaction plays a pivotal role in cellular signaling pathways by regulating the levels of various inositol phosphate isomers, which act as second messengers and mediate diverse cellular processes.

IP4Ks are a family of kinases that exhibit distinct substrate preferences and regulatory mechanisms. They are characterized by their ability to specifically recognize and phosphorylate IP4, particularly the 1,3,4,5-tetrakisphosphate isomer. This phosphorylation event is highly specific and contributes to the fine-tuning of intracellular signaling networks.

The molecular function of IP4K activity can be summarized as follows:

1. **Generation of IP5:** IP4Ks catalyze the conversion of IP4 to IP5 by adding a phosphate group at the 6-position of the inositol ring. This reaction is essential for maintaining appropriate levels of IP5, a key second messenger involved in numerous signaling pathways.

2. **Regulation of IP3 signaling:** IP5 acts as a potent modulator of inositol trisphosphate (IP3) signaling. IP3 is a crucial intracellular messenger responsible for calcium release from intracellular stores. IP5 can interact with IP3 receptors, regulating their activity and influencing calcium homeostasis.

3. **Control of cellular processes:** IP5, generated through the action of IP4Ks, participates in various cellular processes, including:
* **Transcriptional regulation:** IP5 can modulate gene expression by interacting with transcription factors and altering their activity.
* **Cell growth and proliferation:** IP5 plays a role in regulating cell cycle progression and proliferation.
* **Apoptosis and autophagy:** IP5 has been implicated in the regulation of programmed cell death and autophagy, processes essential for cellular homeostasis.
* **Membrane trafficking:** IP5 can influence membrane trafficking events by affecting the activity of proteins involved in vesicle formation and transport.

4. **Signaling network complexity:** IP4K activity contributes to the intricate network of intracellular signaling pathways. The precise role of IP4Ks and their products, IP5, is influenced by their subcellular localization, interaction with other signaling molecules, and the specific cellular context.

5. **Potential therapeutic targets:** Understanding the molecular function of IP4K activity provides insights into the potential therapeutic targets for various diseases. Alterations in IP4K activity have been linked to conditions such as cancer, neurodegenerative disorders, and metabolic diseases.

In summary, inositol tetrakisphosphate 6-kinase activity is an essential enzymatic function responsible for the phosphorylation of IP4 to IP5, which plays a crucial role in regulating intracellular signaling pathways and mediating various cellular processes.'
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Proteins (2)

Compounds (15)