TrkA has five binding domains on its extracellular portion, and the domain TrkA-d5 folds into an immunoglobulin-like domain which is critical and adequate for the binding of NGF.
tˌiːˌɑːɹkˈeɪ ɐ hɐz fˈaɪv bˈaɪndɪŋ dəmˈeɪnz ˌɔn ɪts ˌɛkstɹəsˈɛljʊlɚ pˈoːɹʃən, ænd ðə dəmˈeɪn tˌiːˌɑːɹkˈeɪ ˈeɪdˈiː fˈaɪv fˈoʊldz ˌɪntʊ ɐn ɪmjˈuːnəɡlˌɑːbjʊlˌɪnlˈaɪk dəmˈeɪn wˌɪtʃ ɪz kɹˈɪɾɪkəl ænd ˈædɪkwət fɚðə bˈaɪndɪŋ ʌv ˌɛndʒˌiːˈɛf.