Final answer:
The histone protein that does not form part of the octameric core is H1.
Step-by-step explanation:
The histone protein that does not form part of the octameric core is H1. Histones are DNA binding proteins that play a crucial role in DNA packaging. They are composed of four types of proteins: H2A, H2B, H3, and H4. These four histone proteins form an octamer around which the DNA wraps to form a nucleosome complex. The histone H1, on the other hand, is not part of the octameric core but instead binds to the linker DNA between nucleosomes, helping to further compact the chromatin structure.