Figure 6.

Comparison of the distribution of full-length and truncated proteins within the same muscle cells at three developmental stages (A–C, 1.5-fold; D–F, twofold; and G–I, threefold) shows delayed localization of Δ34, but not Δ30 constructs. Strains in which a truncated or chimeric construct rescues the unc-54(0) mutation were stained with antibody 5–14 (which recognizes an epitope in the MHC A head) to visualize endogenous MHC A. All transgenic proteins, which contain the tagged MHC B head, were detected using anti-HA antibody. In early stages, BHtagΔ34 staining is strong outside the contractile apparatus (arrowheads A′ and D′) compared with MHC A (A and D). Insets show staining in the perinuclear region. The chimera4.tag staining colocalizes with that of MHC A at all stages (B, E, and H), demonstrating that the HA tag, and the MHC B head and tailpiece sequences do not discernibly alter localization. The BHtagΔ30 protein localizes normally at 1.5-fold (C′). Later, embryos expressing Δ30 constructs often show areas in which staining of Δ30 and MHC A are abnormally expanded within or near the plane of the contractile apparatus (arrows in F, F′, I, I′). Transgenic arrays shown are stEx120, stEx118, and stEx154. Bar, 5 μm.