Final answer:
PCNA (Proliferating Cell Nuclear Antigen) is the sliding clamp subunit in eukaryotic cells that stabilizes DNA polymerase during replication.
Step-by-step explanation:
The name of the subunit that acts as the sliding clamp, which keeps the replicating enzyme complex attached to the template in eukaryotic cells, is PCNA (Proliferating Cell Nuclear Antigen). This ring-shaped protein is crucial during DNA replication as it holds DNA polymerase in place, ensuring that the enzyme does not slide off the DNA as it synthesizes new strands. PCNA functions effectively to maintain the stability and progression of the DNA replication fork.