Ligand-binding repeats

Bujo, H., Hermann, M., Kaderli, M.O., Jacobsen, L., Sugawara, S., Nimpf, J., Yamamoto, T., Schneider, W.J. 1994. Chicken oocyte growth is mediated by an eight ligand binding repeat member of the LDL receptor family. EMBO J. 13 5165-5175. 

Forty-four amino acid module characterized by three internal disulfide bridges and an octahedrical cage for a calcium ion. Complement-type repeats are found in many cell surface proteins and form the ligand-binding domain of receptors of the LDL receptor gene family. 

Another group of orphan receptors that as yet have no known ligand bind as homodimers or monomers to direct repeat sequences. 

In a recent study, Mandola et al. showed that the 28 bp TSER tandem repeats contain elements that bind upstream stimulating factor (USF), and also that ligand binding by USF-1 and USF-2 enhances the transcriptional activity of the TS gene (Fig. 2) (42). Electrophoretic mobility shift analysis has shown that the presence of a G-to-C single nucleotide polymorphism (SNP) within the second repeat of the 3R allele leads to decreased ability of upstream stimulatory factor (USF) to bind within the repeat and therefore sequentially result in decreased transcriptional activity of the 3R TS gene variant (42). 

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