Characterization of peroxisomal targeting signals on alanine: glyoxylate aminotransferase.

Proteins destined for the peroxisome matrix or membrane possess distinct targeting signals that engage signal sequence receptors to drive their transport to their final subcellular destination. Peroxisomal targeting signal 1 (PTS1) and 2 (PTS2) are well characterized as signaling the import from the cytosol into the peroxisomal matrix of soluble peroxisomal enzymes. The expression vectors of the enhanced green fluorescent protein (eGFP)-tagged alanine:glyoxylate aminotransferase (AGT) and deletion mutants were introduced into HeLa cells to identify the peroxisomal targeting signal of the AGT. Two sites of the targeting signals into peroxisome, an amino acid sequence containing 59-66 a.a. (8 amino acids) and 389-392 a.a. (4 amino acids, KKKL, but not KKL) on the AGT were clarified. In a three-dimensional structural model, their sites were separately located on the surface of the AGT protein.