Fibroblast growth factor 5 (FGF -5, ENGL. Fibroblast growth factor 5) is a signaling protein of the family of fibroblast growth factor that is present in vertebrates.

FGF -5 is known that it is responsible for the hair length in mammals. Mice in which the gene is destroyed by gene targeting, have greatly prolonged hair. Cause an inhibitory role in the hair growth during the growth phase ( anagen). The FGF5 gene has three exons. In mice and other mammals, the protein exists in two isoforms resulting from alternative splicing of the same RNA transcript. The shorter of the two isoforms lacking the middle exon.

Long hair shapes of domestic dogs, cats and other pets, often referred to as Angora, often carry also a mutation in the FGF -5 gene. Therefore, it was assumed a mutation in this gene could also be related to the long fur of the woolly mammoth. Sequence comparisons between woolly mammoth and various forms of today's elephants, however, were hardly mammoth - specific features in FGF5 gene. Only two differences in the sequence were found. A in the promoter, but not likely to affect the binding of transcription factors and a silent mutation in Exon3, ie one that does not affect the protein sequence. Accordingly, the FGF5 gene does not seem to be responsible for the differences between elephants and woolly mammoths. Can not be completely ruled out a possible influence, however, as for example in the intron regulatory sequences could be that influence gene expression.


  • Growth factor