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. 2005 Dec;17(12):3422–3435. doi: 10.1105/tpc.105.035691

Figure 4.

Figure 4.

Peroxisomal Matrix Protein Import in pex4.

(A) Analysis of matrix protein import using peroxisome-targeted GFPs. Five-day-old wild-type or pex4-1 seedlings expressing GFP modified to contain a PTS1 (Zolman and Bartel, 2004) or PTS2 (Woodward and Bartel, 2005a) signal were examined using fluorescence microscopy. Two root hairs are shown for each line. The punctate pattern indicates peroxisomal protein import. All images were taken at ×100 magnification. Bar = 50 μm.

(B) Analysis of PTS2-GFP and thiolase processing in the wild type, pex4-1, and pex5-1. Immunoblotting using α-GFP (top) or α-thiolase (bottom) was performed on protein samples from 2-d-old untransformed Col-0 (wild type) and wild type, pex4-1, and pex5-1 expressing the PTS2-GFP transgene. The top bands (precursor) represent unprocessed PTS2-GFP or thiolase, the bottom bands represent the mature moiety, and the asterisk marks a cross-reacting protein in the α-GFP panel. pex5-1 (missense mutation in the matrix protein receptor PEX5; Zolman et al., 2000) is shown as a control for PTS2 processing; PEX5 interaction with the PTS2 receptor PEX7 is required for PTS2 matrix protein import (Hayashi et al., 2005; Woodward and Bartel, 2005a). The positions of molecular mass markers (kD) are shown at left.

(C) Analysis of thiolase processing in peroxisome-defective mutants. Immunoblotting using α-thiolase was performed on protein from 3-d-old light-grown seedlings. pex5-1, pex5-10 (T-DNA insertion in PEX5), and pex6-1 (missense mutation in the ATPase PEX6; Zolman and Bartel, 2004) are shown as controls.

(D) Analysis of PEX5 levels in peroxisome-defective mutants. Immunoblotting using α-PEX5 (Zolman and Bartel, 2004) was performed on protein from 3-d-old light-grown seedlings. The top panel shows different exposures of the same membrane to demonstrate similar PEX5 levels in the pex4-1, pex22-1, pex4-1 pex22-1, and pex5-1 mutants; the second exposure shows a lack of intact PEX5 in the pex5-10 mutant. The bottom panel shows the PEX5 membrane reprobed with α-HSC70 as a loading control.