Figure 6.

p62 is required for the formation of GFP-LC3–positive punctuated structures in HeLa cells. (A) HeLa cells transiently transfected with GFP-LC3 alone or cotransfected with siRNA against p62, HA-p62, or HA-p62 D69A were either left in normal medium or starved for amino acids for 1 h. The cells were fixed, and p62 was stained using a p62 mAb. More than 200 randomly selected cells for each condition were scored for the cytoplasmic pattern of GFP-LC3 as either diffuse or punctuate. The frequency of GFP-LC3–positive cells with punctuate localization are indicated to the right. (B) Endogenous p62 as well as coexpressed myc-tagged wild-type p62 or a UBA deletion mutant of p62 coimmunoprecipitated with GFP-LC3 from HeLa cell extracts. GFP or GFP-LC3 was immunoprecipitated from total cellular extracts after cotransfecting the indicated constructs. The cell cultures were either left untreated or starved for amino acids for 1 h as indicated. Copurified endogenous or ectopically expressed myc-tagged p62 constructs were detected using the p62 mAb. Bars, 20 μm.