Fig. 3

Fig. 3 The zebrafish IGFBP-2 cDNA encodes a protein that binds to IGFs but not to insulin and Des(1-3)IGF-I. (A) Ligand blot analysis of CM prepared from the pRc/CMV-IGFBP-2-transfected clones 2, 5, and 6 (lanes 2-4), the pRC/CMV vector-transfected clones 1 and 2 (lanes 5 and 6), and pure bovine IGFBP-2 (lane 1). (B) Affinity crosslinking of [¹²⁵I] IGF-I to zebrafish IGFBP-2 produced by CHO cells (IGFBP-2-transfected clone 2). Binding was competed by the addition of no competitor (lane 2), 500 ng of IGF-I (lane 3), IGF-II (lane 4), Des(1-3)IGF-I (lane 5), and insulin (lane 6). Lane 1 is the negative control that did not have any zebrafish IGFBP-2. The competition of [¹²⁵I] IGF-I was similar in all other IGFBP-2-transfected clones examined (clones 5 and 6). (C) Affinity crosslinking of [¹²⁵I] IGF-II to zebrafish IGFBP-2 produced by CHO cells (IGFBP-2-transfected clone 2). Binding was competed by the addition of no competitor (lane 2), 500 ng of IGF-I (lane 3), IGF-II (lane 4), Des(1-3)IGF-I (lane 5), and insulin (lane 6). Lane 1 is the negative control that did not have any zebrafish IGFBP-2. The competition of [¹²⁵I] human IGF-II was similar in other IGFBP-2-transfected clones examined (clones 5 and 6).