title: ApoA-I-binding protein (AI-BP) and its homologues hYjeF_N2 and hYjeF_N3 comprise the YjeF_N domain protein family in humans with a role in spermiogenesis and oogenesis.
abstract: The screening for additional human YjeF_N domain containing proteins beside the apolipoprotein A-I interacting protein (AI-BP), identified two other genes designated hYjeF_N2-15q23 (formerly human homologue of yeast edc3) and hYjeF_N3-19p13.11 comprising the human YjeF_N family. AI-BP is ubiquitously expressed, with a predominance of these tissues where the homologues were found to be restricted including brain, mammary gland, testes and ovaries. Immunohistochemistry of human testes and ovaries showed an expression of hYjeF_N3-19p13.11 only in Leydig cells and theca cells, respectively, indicating a role in steroid hormone metabolism. Interestingly, the protein was also strongly expressed in Leydig cell tumors and in thecofibromas. The identification of hYjeF_N2-15q23 in theca cells and granulosa cells in ovaries, in human spermatids of meiotic division part II and the apical membrane of Sertoli cells in testes suggest similar functions in oogenesis and sperm maturation which is strengthened by the identification of the spermatogenesis regulator HMGA1 as a conserved transcription factor. However, in contrast to AI-BP, both homologous proteins are unable to bind apoA-I. These results relate the human YjeF_N domain containing protein family to cholesterol processing and steroid hormone metabolism in spermiogenesis and oogenesis, and AI-BP may link this function to the HDL pathway.
authors.affiliation: Institute of Clinical Chemistry and Laboratory Medicine, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Rudolph
authors.forename: A
authors.initials: A
authors.lastname: Sigruener
authors.forename: A
authors.initials: A
authors.lastname: Hartmann
authors.forename: E
authors.initials: E
authors.lastname: Orso
authors.forename: M
authors.initials: M
authors.lastname: Bals-Pratsch
authors.forename: W
authors.initials: W
authors.lastname: Gronwald
authors.forename: B
authors.initials: B
authors.lastname: Seifert
authors.forename: H R
authors.initials: HR
authors.lastname: Kalbitzer
authors.forename: I
authors.initials: I
authors.lastname: Verdorfer
authors.forename: C M
authors.initials: CM
authors.lastname: Luetjens
authors.forename: O
authors.initials: O
authors.lastname: Ortmann
authors.forename: S R
authors.initials: SR
authors.lastname: Bornstein
authors.forename: G
authors.initials: G
authors.lastname: Schmitz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000595:Amino Acid Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics* / Q000502:physiology*; D002675:Child, Preschool; D015342:DNA Probes; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D005350:Fibroma / Q000473:pathology; D015894:Genome, Human; D006801:Humans; D007150:Immunohistochemistry; D007984:Leydig Cell Tumor / Q000473:pathology; D008075:Lipoproteins, HDL / Q000235:genetics* / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009866:Oogenesis / Q000235:genetics* / Q000502:physiology*; D010053:Ovary / Q000166:cytology; D011257:Pregnancy Proteins / Q000235:genetics* / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D019998:Racemases and Epimerases; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013091:Spermatogenesis / Q000235:genetics* / Q000502:physiology*; D013736:Testicular Neoplasms / Q000473:pathology; D013737:Testis / Q000166:cytology
chemical_list: D002352:Carrier Proteins; D015342:DNA Probes; D018076:DNA, Complementary; D008075:Lipoproteins, HDL; D011257:Pregnancy Proteins; D012313:RNA; C052433:NAXE protein, human; D019998:Racemases and Epimerases