Studies on the isolation, structural analysis and tissue localization of fetal antigen 1 and its relation to a human adrenal-specific cDNA, pG2.
Fetal antigen 1 was purified from second trimester human amniotic fluid by immunospecific affinity chromatography followed by reversed-phase chromatography. Fetal antigen 1 is a single chain glycoprotein with a M(r) of 32-38 kDa. The amino acid composition revealed a high content of cysteines, prolines and amino acids (aa) with acidic side-chains indicating that fetal antigen 1 is a compactly folded, strongly hydrophilic molecule. The N-terminal amino acid sequence (37 aa) revealed no homology to other known protein sequences, implying that fetal antigen 1 is a 'novel' human protein. When the aa sequence was back-translated into the appropriate degenerate sequence of nucleic acids, fetal antigen 1 could be partially aligned to a 'human adrenal-specific mRNA, pG2'. The indirect immunoperoxidase technique demonstrated fetal antigen 1 in fetal hepatocytes, glandular cells of fetal pancreas and in fetal adrenal cortex, whereas fetal medullary cells were fetal antigen 1 negative. In adult specimens fetal antigen 1 was exclusively found within the beta cells of the islets of Langerhans and in the adrenals with pronounced staining in the cortex. Our observations suggest that fetal antigen 1 is encoded by the mRNA defined by the cDNA clone pG2, but definitive sequencing and expression studies of this mRNA have not been achieved.
Division of Immunology, State Serum Institute, Copenhagen, Denmark.
C H
CH
Jensen
B
B
Teisner
P
P
Højrup
H B
HB
Rasmussen
O D
OD
Madsen
B
B
Nielsen
K
K
Skjødt
D000311:Adrenal Glands / Q000502:physiology*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000653:Amniotic Fluid / Q000276:immunology*; D000941:Antigens / Q000302:isolation & purification*; D002850:Chromatography, Gel; D004247:DNA; D005260:Female; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009928:Organ Specificity / Q000235:genetics; D011247:Pregnancy
D000596:Amino Acids; D000941:Antigens; D004247:DNA