The two smaller proteins are a medium subunit named μ (mu ∼50 kD) and a small subunit σ (sigma ∼20 kD), and named 1 through 5 corresponding to the 5 AP complexes.
As dúas proteínas pequenas son a subunidade media denominada μ (mu ∼50 kD) e a subunidade pequena σ (sigma ∼20 kD), e denominadas do 1 ao 5 correspondendo cos 5 complexos AP.