What sequence characterizes proteins for sorting to peroxisomes?

Proteins destined for peroxisomes are characterized by a specific targeting signal known as the peroxisomal targeting signal 1 (PTS1), which is a three-amino-acid sequence. This sequence typically consists of the amino acids serine (S), lysine (K), and leucine (L), often represented as SKL or a variant that maintains the crucial last three residues. The presence of this PTS1 signal in the protein's primary structure is recognized by peroxisomal receptors, facilitating the import of the protein into the peroxisome.

Understanding the significance of this specific amino acid sequence is critical, as it underlies the selective process that ensures proteins are correctly transported to the peroxisome, which plays vital roles in fatty acid oxidation and reactive oxygen species detoxification. This specificity distinguishes peroxisome-targeting signals from other organelles, emphasizing the precision of cellular sorting mechanisms.