PaCSs in SH-SY5Y and HL-60 cells.

(A) Ultrastructure of a neuroblastoma SH-SY5Y cell with characteristic PaCSs, enlarged (a1) to show relatively spaced particles and selective FK1 antibody immunogold. In (A) a neural cell process whose hillock-like origin and terminal button abutted on another cell is enlarged in (a2) and (a3), respectively. In (a4) a 20S proteasome-reactive PaCS from a different SH-SY5Y cell is filled with particles and surrounded by ribosomes. (B) Several PaCSs in an HL-60 cell; one of which (b1) shows FK1 immunogold; in (b2) ALFY reactivity of an autophagic vesicle, enlarged in (b3), and non-reactivity of a small PaCS (arrow), enlarged in (b4).