247 CLONING OF THE cDNA OF HUMAN PREGNANCYSPECIFIC β1-GLYCOPROTEIN

Abstract

Human pregnancy-specific β 1-glycoprotein (βSPl) is detected in increasing concentration in maternal serum starting from the first 2–3 weeks of pregnancy. Decreased levels of this protein are often associated with fetal distress or ectopic pregnancy. It is not detectable in the healthy male and in the nonpregnant female. The protein has Mr of 90,000. Its structure and function is unknown. Cloning of the cDNA of this protein will permit characterization of its structure and study of its function and regulation throughout pregnancy. Rabbit antihuman β SP1 antibody was absorbed with other placental proteins and affinity purified. The 1–125 labeled antibody was used as probe to screen a human placental cDNA expression library in bacteriophage λgt 11 provided by Dr. Brian Knoll. Six positive clones were identified. Lysates of bacteria carrying these 6 recombinant phage were prepared and analyzed by Western blot. A slow moving protein band hybridizing with the probe was identified in lysates. No such bands were observed in lysates of the host bacteria or the wild type λgt 11 lysogen. These results confirmed that in all cases the antibody recognized the cDNA translation product and not a phage or bacterial protein. Eco RI digestion of the recombinant phage DNA showed inserts of size varying from 415 to 2803 bp with two internal Eco RI sites in the 2803 bp insert. We thank Dr. Hans Bohn of Behringwerke for the purified β SPl and Drs. Dominic Chung and Earl Davie for their help and advice. (Supported in part by NIH grant HD 16730).

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