Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest Trafficking of Protein II Lecture PPT
Transport into the nucleus
? Proteins similar to importins, referred to as exportins, are
involved in the export of
many macromolecules (various
proteins, tRNA molecules, ribosomal subunits and
certain mRNA molecules) from the nucleus
? Cargo molecules for export carry nuclear export signals
(NESs).
? Ran proteins are involved in this process also
? The family of importins and exportins are referred to as
karyopherins
? Another system is involved in the translocation of the
majority of mRNA molecules.
? These are exported from the nucleus to the cytoplasm as
ribonucleoprotein (RNP) complexes attached to a protein
named mRNP exporter
Peroxisomes
Transport into peroxisomes
Transport into peroxisomes
? Peroxins - peroxisome transport receptors
? Bind to proteins with PTS1 and dock to the
translocation channel
? The complex is transported through the membrane
? Protein is released
? Peroxin is recycled
Zellweger syndrome
? Usually caused by mutations in genes encoding certain
proteins--the PEX family of genes, also called peroxins
--involved in various steps of peroxisome biogenesis
? Number of peroxisomes can vary from being almost
normal to being virtually absent in some patients
? Apparent at birth and is characterized by profound
neurologic impairment, victims often dying within a year
? Biochemical findings include an accumulation of very-
long-chain fatty acids, abnormalities of the synthesis of
bile acids, and a marked reduction of plasmalogens
? Two closely related conditions are neonatal
adrenoleukodystrophy and infantile Refsum disease.
This post was last modified on 30 November 2021