Sunday, October 16, 2011

Agouti gene - what is it?

The agouti gene is probably the best known of the genes in the cat breeding world (the cat fancy). It is one of genes that is responsible for the tabby cat. If a cat has banded or ticked hair strands the cat carries the dominant agouti gene symbolized by the letter A. This gene signals the creation of the dark and light agouti banding on each hair. Alternately the non-agouti gene (a/a) signals the creation of solid colored hairs.

The agouti gene signals the on-off creation of eumelanin a pigment produced in a cell called a melanocyte. Eumelanin is black-brown in color. When the agouti gene has not signalled the creation of eumelanin a pigment called phaeomelanin is produced in the melanocyte. Phaeomelanin is red-yellow in color. The melanocyte feeds the pigment into the hair follicle.
Tabby cat hair strand showing banding of pigmentation

The message (signal) to create these two different types of pigment is effected by the action of a protein molecule called the agouti peptide and a hormone called the Melanocyte Stimulating Hormone (MSH).

The tabby gene dictates how the hairs are positioned throughout the body so it dictates how the tabby pattern appears. It works in conjunction with the agouti gene to create the well known tabby cat of which there are three types: classic blotched, spotted and mackerel or striped.

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