Final answer:
The prokaryotic DNA polymerase III holoenzyme's integrity is maintained by a σ (sigma) subunit, which, combined with the four other core subunits (α, α, β, and β'), constitutes the complete holoenzyme responsible for proper initiation of transcription.
Step-by-step explanation:
The prokaryotic DNA polymerase III holoenzyme is held together by multiple subunits. Essential to this complex is the σ (sigma) subunit, which is involved only in transcription initiation.
The polymerase is composed of five polypeptide subunits, two of which are identical, denoted as α (α), α (α), β (β), and β' (β'), which constitute the core enzyme. The presence of the σ subunit, in addition to these core subunits, forms the complete holoenzyme responsible for initiating the process of transcription accurately.