A discrete domain of the human TrkB receptor defines the binding sites for BDNF and NT-4.
TrkB is a member of the Trk family of tyrosine kinase receptors. In vivo, the extracellular region of TrkB is known to bind, with high affinity, the neurotrophin protein brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4). We describe the expression and purification of the second Ig-like domain of human TrkB (TrkBIg(2)) and show, using surface plasmon resonance, that this domain is sufficient to bind BDNF and NT-4 with subnanomolar affinity. BDNF and NT-4 may have therapeutic implications for a variety of neurodegenerative diseases. The specificity of binding of the neurotrophins to their receptor TrkB is therefore of interest. We examine the specificity of TrkBIg(2) for all the neurotrophins, and use our molecular model of the BDNF-TrkBIg(2) complex to examine the residues involved in binding. It is hoped that the understanding of specific interactions will allow design of small molecule neurotrophin mimetics.
Naylor
Ruth L
RL
University Research Centre for Neuroendocrinology (Care of the Elderly), Bristol Royal Infirmary, Bristol, BS2 8HW, United Kingdom.
Robertson
Alan G S
AG
Allen
Shelley J
SJ
Sessions
Richard B
RB
Clarke
Anthony R
AR
Mason
Grant G F
GG
Burston
Judy J
JJ
Tyler
Sue J
SJ
Wilcock
Gordon K
GK
Dawbarn
David
D
D000595:Amino Acid Sequence; D001665:Binding Sites; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism*; D002942:Circular Dichroism; D006801:Humans; D007128:Immunoglobulin Fragments / Q000737:chemistry; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D020813:Receptor, trkB / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D020349:Surface Plasmon Resonance
D019208:Brain-Derived Neurotrophic Factor; D007128:Immunoglobulin Fragments; D009414:Nerve Growth Factors; D020813:Receptor, trkB; C073922:neurotrophin 4