Cellulose is a compound used in a variety of materials. Ying Gu, associate
professor of biochemistry and molecular biology at The Pennsylvania State
University (Penn State) said that cellulose makes up about 95 percent paper
and 90 percent cotton, and its derivatives are even used as emulsifiers in
ice cream.

Cellulose has also been considered as a major component of biofuels, and the
knowledge of cellulose synthesis could help optimize its use as a renewable
energy resource. Penn State researchers have identified the major steps in
the process as well as the tools that plant cells use to create cellulose,
including proteins that transport critical components to the location where
cellulose is made.

Gu said that it has been known that cellulose is synthesized in the plasma
membrane that surrounds plant cells called the cellulose synthase complex,
and that the main component of this complex is a unique cargo protein called
cellulose synthase. What is unknown is, if other proteins are involved in
the complex, or how the proteins get to the plasma membrane. To answer these
questions, the researchers used different approaches to create a timeline of
events and to identify the main proteins involved in preparing the cell for
synthesis.

The researchers showed that a protein called cellulose synthase interactive
1 (CSI1) interacts with the cellulose synthase complex before synthesis and
may help mark the site at the plasma membrane where synthesis occurs. They
also demonstrated that CSI1 interacts with a separate complex called the
exocyst complex, which is involved in transporting materials to the plasma
membrane in a variety of species, and a protein called PATROL1. These
components may contribute to how quickly the cellulose synthase complex
travels to the cell's outer membrane before synthesis. Because CSI1
interacts with many components that are important to cellulose synthesis,
the research team plans to use it as a tool to further explain this
important process and its evolution.

[science.psu.edu]