Crystal structure of human chorionic gonadotropin.

Lapthorn, A J; Harris, D C; Littlejohn, A; Lustbader, J W; Canfield, R E; Machin, K J; Morgan, F J; Isaacs, N W · Nature · 1994

basic_science · Level V

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Abstract

The three-dimensional structure of human chorionic gonadotropin shows that each of its two different subunits has a similar topology, with three disulphide bonds forming a cystine knot. This same folding motif is found in some protein growth factors. The heterodimer is stabilized by a segment of the beta-subunit which wraps around the alpha-subunit and is covalently linked like a seat belt by the disulphide Cys 26-Cys 110. This extraordinary feature appears to be essential not only for the association of these heterodimers but also for receptor binding by the glycoprotein hormones.

Medical subject headings