title: Study of the binding of motilin to the membranes of enterocytes from rabbit jejunum.
abstract: The results obtained in the present work have shown that [125I]motilin bound specifically to basolateral (BL) membrane but it did not bind to the brush border (BB) membrane of the rabbit jejunum enterocyte. The [125I]motilin dissociation constant (Kd) was 95.58 +/- 15.0 pM and the receptor density (Bmax) was 2.54 +/- 0.40 fmol/mg protein. The binding of [125I]motilin to BL membrane was competitively inhibited by both unlabeled motilin and erythromycin. The IC50s were (2.1 +/- 0.4) 10(-8) M and (1.3 +/- 0.1) 10(-6) M for motilin and erythromycin, respectively, and the Ki were (6.83 +/- 1.3) 10(-9) M for motilin and (4.32 +/- 0.33) 10(-7) M for erythromycin. Saturation and competition binding studies showed interaction at only one class of binding sites in BL membrane.
authors.affiliation: Departamento de Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Spain.
authors.forename: A I
authors.initials: AI
authors.lastname: Alcalde
authors.forename: M A
authors.initials: MA
authors.lastname: Plaza
authors.forename: R
authors.initials: R
authors.lastname: Marco
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D007583:Jejunum / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D009037:Motilin / Q000378:metabolism*; D011817:Rabbits; D011869:Radioligand Assay; D011964:Receptors, Gastrointestinal Hormone / Q000032:analysis* / Q000378:metabolism; D018013:Receptors, Neuropeptide / Q000032:analysis* / Q000378:metabolism
chemical_list: D011964:Receptors, Gastrointestinal Hormone; D018013:Receptors, Neuropeptide; C050802:motilin receptor; D009037:Motilin