Final answer:
The code writer subunit in chromatin remodeling functions to regulate gene expression by altering the chromosomal structure, thus controlling the accessibility of DNA for transcription. This includes sliding nucleosomes and making histone modifications that either open or close chromosomal regions.
Step-by-step explanation:
The function of the code writer subunit in chromatin remodeling is to regulate gene transcription by altering the chromosomal structure, thereby making DNA either accessible or inaccessible to transcription machinery. Chromatin remodeling is crucial for determining whether a gene is actively transcribed or silenced. This process involves histone modifications such as acetylation and methylation, facilitated by enzymes like histone acetyltransferases and methyltransferases. Additionally, complexes that hydrolyze ATP, such as the FACT complex, are key in moving or sliding nucleosomes to either open up the chromosomal region for the binding of RNA polymerase and transcription factors or to restore the nucleosomes after transcription.
These modifications provide signals that direct the nucleosomes to slide, thereby opening the chromosomal regions for transcription or, alternatively, signal a closed configuration that inhibits access by transcription factors. This complex orchestration of modifications and the sliding of nucleosomes play a critical role in the epigenetic regulation of gene expression, which can have profound implications for cancer development as faulty chromatin remodeling can result in aberrant cell cycling and gene expression.