Structural requirements of the extracellular to transmembrane domain junction for erythropoietin receptor function - PubMed (original) (raw)

. 2005 Apr 15;280(15):14844-54.

doi: 10.1074/jbc.M411251200. Epub 2005 Jan 18.

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Structural requirements of the extracellular to transmembrane domain junction for erythropoietin receptor function

Katharina F Kubatzky et al. J Biol Chem. 2005.

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Abstract

The erythropoietin receptor (EpoR) is crucial for erythrocyte formation. The x-ray crystal structures of the EpoR extracellular domain lack the juxtamembrane (JM) region and the junction to the transmembrane (TM) domain. Yet the JM-TM regions are important for transmitting the conformational change imposed on the receptor dimer by Epo binding. Cysteine-scanning mutagenesis of the JM-TM regions identified three novel constitutively active mutants, demonstrating close disulfide-bonded juxtapositioning of these residues in the JM (L223C) and N-terminal TM domain (L226C, I227C). Chemical cross-linking defined the interface of the active helical TM dimer and revealed that the JM-TM segment encompassing Leu(226)-Leu(230) is non-helical. Molecular dynamics and NMR studies indicated that the TM-JM junction forms an N-terminal helix cap. This structure is important for EpoR function because replacement of this motif by consecutive leucines rendered the receptor constitutively active.

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