KIF1B

The KIF1B gene provides instructions for making a protein called kinesin family member 1B, part of the kinesin family of proteins. These proteins are essential for the transport of materials within cells. Kinesin proteins function like freight trains that transport cargo, and their structure is suited for this cargo-carrying function. One part of the protein, called the motor domain, powers the protein and its cargo along a track-like system made from structures called microtubules. Another part of the kinesin protein, which varies among family members, binds to specific materials for transport.

Research suggests that the kinesin family member 1B protein specializes in carrying two types of cargo. In nerve cells, this protein transports small, saclike structures called synaptic vesicles, which contain materials necessary for the transmission of nerve impulses. In other cell types, the kinesin family member 1B protein carries energy-producing structures called mitochondria.

Charcot-Marie-Tooth disease - caused by mutations in the KIF1B gene

One KIF1B gene mutation has been detected in some patients with a form of Charcot-Marie-Tooth disease known as type 2A. The mutation changes one of the protein building blocks (amino acids) in the motor domain of kinesin family member 1B. Specifically, the amino acid glutamine is replaced by the amino acid leucine at protein position 98 (written as Gln98Leu). Although the effect of this mutation is not fully understood, the motor function of the protein and the transport of synaptic vesicles are probably disrupted. Lowered levels of synaptic vesicles at nerve endings could impair the transmission of nerve impulses, causing the symptoms of type 2A Charcot-Marie-Tooth disease.