A new cDNA clone relating to larger molecular species of rat insulin-like growth factor-I mRNA.

A new cDNA clone for rat IGF-I mRNA was obtained. The cDNA contained a new base sequence as cDNA in the 3' region. The sequence coincided with a part of the sequence reported earlier by Shimatsu and Rotwein in exon 5 of the rat IGF-I gene. The presence of this cDNA proved the previous suggestion to be true that the size heterogeneity of IGF-I mRNA is primarily due to the heterogeneity of the 3'-untranslated region.