H1-5 (H1.5 linker histone) is a chr6-organizing protein that binds to nucleosomes and regulates multiple cellular processes through chr6 architecture modulation. H1.5 facilitates chr6 compaction and three-dimensional genome organization, with mutations in H1 genes acting as genetic drivers in B cell lymphomas by disrupting chr6 architecture and leading to derepression of developmentally silenced genes 1. The protein shows specific nuclear localization patterns, being universally enriched at the nuclear periphery and co-localizing with compacted DNA, distinct from other H1 variants 2. H1.5 contributes to centromere integrity by directly interacting with CENP-A nucleosomes, and its knockdown results in loss of centromeric α-satellite transcription, reduced CENP-A loading, and mitotic defects 3. Additionally, H1.5 regulates alternative splicing by binding over splice sites of short exons, where its association correlates with exon inclusion levels and RNA polymerase II stalling 4. The protein is downregulated in ovarian granulosa cell tumors compared to normal ovarian tissues, suggesting potential diagnostic significance 5. These functions establish H1.5 as a multifunctional chr6 regulator involved in genome organization, transcriptional control, centromere function, and RNA processing.