Table 1 of
Seigel, Mol Vis 2000;
Table 1. Characteristics of IGF-1 and analogs
IGF-1 analogs listed in Table 1 exhibit altered affinities to the type 1 IGF-1 receptor and IGF-1 binding proteins and can be used to determine their relative importance in regulating the biological activity of IGF-1 [33-36] LongR3IGF-1 is reported to be significantly more potent than native IGF-1, presumably due to the decreased binding of LongR3IGF-1 to all IGF-1 binding proteins, which would normally inhibit the biological actions of IGF-1 . In comparison, the [Ala31]IGF-1 analog has somewhat reduced binding to the IGF-1 receptor, greater affinity for IGF-1 binding proteins, and less stimulation of protein synthesis. The [Leu24][Ala31]IGF-1 analog has undetectable binding to the IGF-1 receptor, but normal binding affinities to IGF-1 binding proteins, and little stimulation of protein synthesis. The [Leu24][Ala31]IGF-1 analog is ideal for investigating IGF-1 actions largely independent of binding to the IGF-1 receptor. With the use of these three analogs in comparison with authentic IGF-1, we tested whether IGF-1-mediated neuroprotective mechanisms depended upon strong interactions between IGF-1 and the IGF-1 receptor or IGF-1 binding proteins. All values expressed as ED50 (ng/ml), the median effective dose (concentration) as determined by interpolation from a dose-effect curve. Data were summarized from product specification sheets provided by GroPep, Ltd. (Adelaide, Australia).
IGF-1 R1 Affinity for Stimulation IGF-1 Affinity for Stimulation IGF-1 and Receptor-1 IGF-1 Binding of Protein Analogs Binding Proteins Synthesis -------------- ---------- ------------- ----------- IGF-1 5 4 11 LongR3 18 >1000 2 [Ala31] 19 1 38 [Leu24][Ala31] >750 3 >2000