Question

In which way does peroxisomal protein import differ from mitochondrial protein import?

A. Ubiquitination is a key step in receptor cycling

B. Peroxisomal proteins do not requires signal sequences for import

C. Peroxisomal protein import is co-translational

D. Peroxisomes use the same mechanism for import of matrix and membrane proteins

Answer 1

The Protiens for transport to peroxisome is translated into cytosol which has either N-terminus or C-terminus peroxisomal targeting sequence 1 (PTS-1). PTS-1 are the sequence of 3 amino acid ser-lys-leu which are recognized by Pex5, the cytosolic receptor Protien. Pex5 with the bound matrix protein interact with Pex14 receptor located on peroxisome membrane. Ubiquitination and deubiquitination mechanism is used to recycle the Pex5 into cytosol.

All the Protiens are targeted to peroxisome post-translationally means after synthesis in cytosol. Peroxisome membrane and matrix proteins are incorporated by different pathway.

Hence option A is correct .