We recently reported two naturally occurring polymorphisms of the human serotonin 1A receptor: glycine22 → serine (Ser22) and isoleucine28 → valine (Val28) (Kobilka et al. 1987;Chanda et al. 1993) coded by an intronless gene located on chromosome 5 at 5q11.2-q13 (Kobilka et al. 1987). Like other members of the G-protein-coupled receptor family (Dohlman et al. 1991), the 5-HT 1A receptor consists of seven transmembrane hydrophobic domains, with an extracellular aminoterminal domain and a cytoplasmic carboxyl-terminus. By coupling with the G i/o family of heterotrimeric G proteins, the 5-HT 1A receptor has been shown to either inhibit or activate adenylate cyclase activity, open potassium channels, close calcium channels, and inhibit phosphatidylinositol turnover (reviewed in Boess and Martin 1994). The 5-HT 1A receptor is expressed both presynaptically on the cell bodies and the dendrites of serotonergic neurons located in the raphe nuclei and postsynaptically with the highest density in the limbic system (Zifa and Fillon 1992;Burnet et al. 1995).The 5-HT 1A receptor is believed to play a role in a variety of behaviors, such as aggression, sexual behavior, and appetite control, and in several psychiatric disorders, such as mood disorders, anxiety disorders, anorexia ner-

The human 5-HT1A receptor was screened for naturally occurring mutations. The PCR product of the 5-HT1A receptor gene was digested with several restriction enzymes and evaluated by single-strand conformational polymorphism (SSCP) analysis. Comparison of the SSCP electrophoretic pattern with a restriction map of the 5-HT1A receptor allowed localization of the polymorphic sites facilitating their identification by sequence analysis. Two polymorphisms were identified in the human 5-HT1A receptor gene that altered amino acid composition. The polymorphisms encode amino acid substitutions in the 5-HT1A receptor of a glycine to serine at amino acid 22 and an isoleucine to valine at amino acid 28, respectively. Both polymorphisms alter the extracellular amino terminal domain of the 5-HT1A receptor. The polymorphic 5-HT1A alleles have been found in American and Finnish Caucasians and in native American Indians. This is the first report of a polymorphism in the human 5-HT1A receptor gene that alters the structure of the 5-HT1A receptor protein composition.

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Human chorionic gonadotropin (hCG) is 8 product of the rrophoblast, With the exception of trophoblast,ic and some other cancers where oncofct,al genes are expressed, the rise in hCG in blood is indicative of pregnancy. hCG is being extensively used for induction of ovulation in women and for treatment of mate infertility. One of the demonstrated roles of hCCi is the rescue of the corpus lureurn leading co the continued secretion of progesterone, which in turn sustains the endometrium and prevents its menstrual shedding. The critical role of hCG in maintaining early pregnancy is confirmed by the ability of anti-KG antibodies, induced by active [l] or passive immunization 121, to terminate pregnancy in primates. Birth control vaccines based on ihe @'-subunit of hCG are currc:tt!y under clinical trials [3]. hCG belongs io a g:tii.ip of g!ycoprotein hormones consisting of two non-identical subunits designated CY and ,8, which sion vectors under the control of mctallothionine-1 promoter [7,8] or SV40 early promoter [O]. Conventionally purified native hCG is dissociated to obtain the subunit protein. This, however, entails recovery losses and is invariably contaminated with trace amounts of the other subunit. One of the objectives of the present work was to express the N subunit of hCG independently by recombinant DNA technology. The baculovirus expression vector system utilizing AcNPV and Sf9 cells has shown great potential for the synthesis of a variety of proteins [lo]. Correct processing of exported proteins as well as post-translational modifications, have been reported to take place in this system [ 11,121. The levels of expression (0.5-800 mg/l) are much higher than other expression systems making it an attractive alternative.We report here on the expression of the (Y subunit of hCC.i in insect cells infected with a recombinant bacuko-* -vxss c~::lin_e the cthCG, and characterization of the recombinant subunir ill terms of its immunological and biological properties. We also present evidcncc that the bulk of the cvhCG synthesized by the insect cells is not secreted into the medium, perhaps due to a 'secretory load' on the system. Finally, the implications of using a very late promoter for the synthesis of an extensively modified protein using baculovirus expression vector system are discussed. 2, MATERIALS AND METHODS Virus and cellsThe recombinant baculovirus -vAcculaCG -was constructed, characterized and plaque-purified as described 1133. AcNPV and 104Published by Elsevier Science Publishers e3. V.