Switching signals

Kinase proteins control cell processes

Hormone systems often act through a sequence in which the hormone binds to its receptor on the outside of the cell to activate the enzyme inside the cell. This system allows a signal carried by small amounts of a hormone to be amplified inside the cell. Typically, the enzyme involved, a kinase, adds a small chemical group (a phosphate) onto another protein. Protein kinases regulate many interactions in cells. The insulin receptor, for example, operates by turning on a protein kinase when insulin binds.

BRAF is a human gene that contains the information to make a protein called BRAF. BRAF is an enzyme that regulates cell growth. To be active, the BRAF protein usually requires a signal from outside the cell. However, some mutations make it permanently active as a kinase, even without this signal.

Some inborn mutations in BRAF cause growth disorders. Some mutations, which can also arise in individual cells later in life, can lead to uncontrolled cell growth – cancer. The skin cancer melanoma is often associated with BRAF mutations, for example. Several chemicals that inhibit BRAF show promise as potential cancer treatments, but they will need to be tested in clinical trials before they can be used in hospitals.

About this resource

This resource was first published in ‘Proteins’ in January 2014.

Biotechnology and engineering, Cell biology
Education levels:
16–19, Continuing professional development