Rat placental lactogen-I variant (rPL-Iv), product of an unique gene, is biologically different from rPL-I

Endocrinology
M C RobertsonR P Shiu

Abstract

The rat placenta expresses two rat placental lactogen-I (rPL-I) proteins: the normal rPL-I in the first half of pregnancy and a variant (rPL-Iv) in the second half of pregnancy. They are 70% identical at the amino acid level but arise from different cell types: rPL-I from giant cells and rPL-Iv from cytotrophoblasts. To assess whether rPL-Iv originates from alternative splicing of the rPL-I gene or is the product of a separate gene, genomic clones of rPL-I and rPL-Iv were isolated from a lambda EMBL-3 rat genomic library. Restriction enzyme analysis of the 14-kilobase full-length genomic clones of rPL-I and rPL-Iv indicated that the two genes are distinct. To assess the biological activity of the variant protein relative to other members of the rat PL/PRL/GH family, two expression systems were chosen to obtain the purified recombinant protein: 1) a secreted form of rPL-Iv was obtained from Chinese hamster ovary (CHO) cells transfected with rPL-Iv-complementary DNA; and 2) a rPL-Iv fusion protein (Bac-rPL-Iv) was obtained from Spodoptera frugiperda (Sf9) insect cells that had been infected with a recombinant baculovirus generated from rPL-Iv complementary DNA. An antibody was generated to the purified Bac-rPL-Iv fusion protein a...Continue Reading

Citations

Aug 10, 2006·Mammalian Genome : Official Journal of the International Mammalian Genome Society·S M Khorshed AlamMichael J Soares
Oct 4, 2000·Physiological Reviews·M E FreemanG Nagy

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