title: Source and hormone-dependence of Gix-gp70 in mouse serum.
abstract: The gp70 family of glycoproteins is distinguished by the role of these molecules as constituents of C-type viral envelopes and also as Mendelian cellular constituents expressed independently of virus production. The source of G(IX)-gp70 in the serum of 129 strain mice, which are not overt producers of virus, could not be traced to any organ or tissue that is known to be G(IX)-positive by serological tests. Hematopoietic tissues were excluded as source of serum G(IX)-gp70 by tests with reciprocal radiation chimeras made from 129 and 129-G(IX)(-) donors and recipients. Thymus and spleen were excluded because excision of these organs did not affect levels of G(IX)-gp70 in the serum. The serum of young adult 129 males contains roughly four times as much G(IX)-gp70 as adult 129 females and the levels rise in both sexes with increasing age. Castration of 129 males reduced the level of serum G(IX)-gp70 to that of females, and the level was fully restored by testosterone. Thus the epididymis and seminal fluid, though rich in G(IX)-gp70, do not contribute significant amounts of G(IX)-gp70 to the serum. The level of G(IX)-gp70 in the serum of testosterone-treated females, though more than double that of untreated females, did not reach the level of normal males, under the conditions tested. This may signify that G(IX)-gp70 production by males is subject to imprinting by testosterone in early life. Evidently the main source of serum G(IX)-gp70 is a tissue or organ that is common to males and females, is directly or indirectly responsive to testosterone, and has not so far been identified serologically as G(IX)- positive.
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000032:analysis*; D002369:Castration; D005260:Female; D006023:Glycoproteins / Q000097:blood; D008297:Male; D008657:Metabolic Clearance Rate; D051379:Mice; D011828:Radiation Chimera; D012190:Retroviridae / Q000276:immunology / Q000378:metabolism*; D012737:Sex Factors; D013156:Splenectomy; D013739:Testosterone / Q000494:pharmacology*; D013934:Thymectomy; D014764:Viral Proteins / Q000097:blood*
chemical_list: D000956:Antigens, Viral; D006023:Glycoproteins; D014764:Viral Proteins; D013739:Testosterone