Yes, histones protein synthesis occurs during S phase.

Histones are a type of protein that play a crucial role in packaging and organizing DNA into chromatin within the nucleus of eukaryotic cells. The synthesis of histones is tightly regulated in the cell cycle to ensure proper DNA replication and cell division.

Timing of Histone Protein Synthesis:
- Histones are synthesized during the S phase of the cell cycle, which is the phase where DNA replication takes place.
- The synthesis of histones is coordinated with DNA replication to ensure that newly replicated DNA is properly packaged into chromatin.

Importance of Histone Protein Synthesis:
- Proper histone synthesis is essential for maintaining the integrity of the genome and regulating gene expression.
- Histones help to compact DNA into chromatin, which is important for the regulation of gene transcription and DNA replication.

Regulation of Histone Protein Synthesis:
- The synthesis of histones is tightly regulated by various factors, including cell cycle checkpoints and signaling pathways.
- Dysregulation of histone synthesis can lead to genomic instability and disease.

In conclusion, histone protein synthesis occurs during the S phase of the cell cycle to ensure proper packaging of DNA into chromatin. This process is tightly regulated and essential for maintaining genome integrity and proper gene expression.