Expression of the human growth hormone variant gene in cultured fibroblasts and transgenic mice.

The nucleotide sequence of the human growth hormone variant gene, one of the five members of the growth hormone gene family, predicts that it encodes a growth hormone-like protein. As a first step in determining whether this gene is functional in humans, we have expressed a mouse metallothionein I/human growth hormone variant fusion gene in mouse L cells and in transgenic mice. The growth hormone variant protein expressed in transiently transfected L cells is distinct from growth hormone itself with respect to reactivity with anti-growth hormone monoclonal antibodies, behavior during column chromatography, and isoelectric point. Transgenic mice expressing the growth hormone variant protein are 1.4- to 1.9-fold larger than nontransgenic controls, suggesting that the protein has growth-promoting properties.