This locks the HIV genome into the capsid:

Explanation

The HIV Gag protein is responsible for packaging and locking the viral genome inside the capsid because its nucleocapsid (NC) domain specifically binds the RNA packaging signal (Ψ) and tethers the genome during assembly, while its capsid (CA) domain polymerizes to form the protective shell. In contrast, Pol encodes enzymes (protease, reverse transcriptase, and integrase) that are co-packaged but do not mediate genome encapsidation, and Env forms the envelope glycoproteins for viral entry, playing no role in capsid assembly or RNA packaging.