Figure 6.

Intracellular targeting of ZIP by PKC-ζ but not by ERK. COS cells were cotransfected with expression vectors encoding myc-tagged ZIP and PKC-ζ (A–D) or myc-ZIP and ERK2 (E and F). After 40 hr cells were fixed and proteins were visualized by indirect immunofluorescence. ZIP was detected by fluoresceine (green), PKC-ζ, and ERK by rhodamine (red). Double exposures (C and D) (yellow) show the overlapping fluorescence of ZIP and PKC-ζ. (A–C) The left cell only expresses ZIP and shows punctate staining, the right cell coexpresses ZIP and PKC-ζ and shows diffuse staining of ZIP. (D) In the two yellow cells ZIP and PKC-ζ colocalize, the cell at the top right only expresses ZIP. (E and F) Despite coexpression of the unrelated protein kinase ERK (red) ZIP (green) does not show even distribution but is still aggregated. Nuclei are stained with 4′,6-diamidino-2′-phenylindole.