Components responsible for transport between successive Golgi cisternae are highly conserved in evolution

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Glycoprotein transport between Golgi compartments is crucial for protein maturation.
• An in vitro system requires cytosolic components and ATP for this transport.
• The specific requirements of acceptor Golgi fractions and cytosolic factors were not fully understood across diverse organisms.

Purpose of the Study:

• To investigate the cross-species conservation of essential components for intra-Golgi transport.
• To determine if Golgi fractions from various organisms can act as acceptors in an in vitro transport assay.
• To assess the functional conservation of cytosolic factors involved in post-translational protein transport.

Main Methods:

• Reconstitution of glycoprotein transport in an in vitro system using Golgi and cytosolic fractions.
• Testing the acceptor activity of mammalian Golgi fractions.
• Evaluating the ability of cytosolic fractions from plants, animals, and lower eukaryotes to support transport.
• Fractionation of wheat germ cytosol and complementation assays with bovine brain cytosol.

Main Results:

• All tested mammalian Golgi fractions functioned as effective acceptors in the in vitro assay.
• Cytosol from plants, animals, and a lower eukaryote could substitute for homologous Chinese Hamster Ovary (CHO) cytosol.
• A wheat germ cytosol subfraction complemented a bovine brain cytosol fraction, indicating functional conservation.

Conclusions:

• The key components mediating post-translational protein transport within the Golgi apparatus are highly conserved.
• This conservation extends across plants, animals, and lower eukaryotic organisms.
• The findings support a conserved molecular machinery for intra-Golgi glycoprotein trafficking.