The gp70s isolated from normal mouse tissues by radioimmune precipitation and SDS-polyacrylamide gel electrophoresis (SDS-PAGE) were shown to be highly pleomorphic. Their apparent molecular weights calculated from SDS-PAGE ranged from 75000 for thymus gp70 to 65000 for epididymal secretion gp70. Differences in the Mr of tissue-associated gp70s were confirmed by double-label co-electrophoresis studies. In addition, a high degree of primary structural pleomorphism among tissue-associated gp70s was demonstrated using two-dimensional tryptic peptide fingerprint analysis. These studies showed that most of the conserved peptides of tissue-associated gp70s were also common to xenotropic murine leukaemia virus (MuLV) gp70s. Thus, tissue-associated gp70s are probably encoded by endogenous xenotropic MuLV env genes or gene fragments. Tissue-associated gp70s also showed a very high level of primary structural pleomorphism. These phenomena were observed for gp70s derived from the tissues of several strains of mice. Tissue-associated gp70 pleomorphism may arise as a consequence of at least two simultaneously operating mechanisms. First, the expression of pleomorphic forms of gp70s on murine tissues may be regulated by mechanisms that also determine the differentiated state of the tissues. Second, endogenous xenotropic env genes may be modified by recombinational or mutational events among these genes, or among cellular genes that regulate the expression of endogenous proviral genes.
BucklerC. E.,
HogganM. D.,
ChanH. W.,
SearsJ. F.,
KhanA. S.,
MooreJ. L.,
HartleyJ. W.,
RoweW. P.,
MartinC. A.1982; Cloning and characterization of an envelope-specific probe from xenotropic murine leukemia proviral DNA. Journal of Virology 41:228–236
ChanH. W.,
BryanT.,
MooreJ. L.,
StaalS. S.,
RoweW. P.,
MartinM. A.1980; Identification of ecotropic proviral sequences in inbred mouse strains with a cloned subgenomic fragment. Proceedings of the National Academy of Sciences, U. S. A 77:5779–5783
CollettM. S.,
EriksonR. L.1978; Protein kinase activity associated with the avian sarcoma virus src gene product. Proceedings of the National Academy of Sciences, U. S. A 75:2021–2024
Del VillanoB. C.,
LernerR. A.1976; Relationship between the oncornavirus gene product and a major protein secretion of the mouse genital tract. Nature, London 259:497–499
ElderI. H.,
PickettR. A.,
HamptonJ.,
LernerR. A.1977; Polymorphism of the major envelope glycoprotein (gp70) of murine C-type viruses: virion associated and differentiation antigens encoded by a multigene family. Nature, London 267:23–28
ElderJ. H.,
GautschJ. W.,
JensenF. C.,
LernerR. A.,
ChusedT. M.,
MorseH. C.,
HartleyJ. W.,
RoweW. P.1980; Differential expression of two distinct xenotropic viruses in NZB mice. Clinical Immunology and Immunopathology 15:493–501
FamulariN. G.,
BuchhagenD. L.,
KlenkH.-D.,
FleissnerE.1976; Presence of murine leukemia virus envelope proteins gp70 and p15(E) in a common polyprotein precursor of infected cells. Journal of Virology 20:501–508
GibsonW.1974; Polyoma virus proteins: a description of the structural proteins of the virion based on polyacrylamide gel electrophoresis and peptide analysis. Virology 62:319–336
KennelS. J.,
FeldmanJ. D.1976; Distribution of viral glycoprotein gp69/71 on cell surfaces of producer and non-producer cells. Cancer Research 36:200–208
KesslerS. W.1975; Rapid isolation of antigens from cells with a staphylococcal protein A-antibody adsorbent: parameters of the interaction of antibody-antigen complexes with protein A. Journal of Immunology 115:1617–1624
McClintockP. R.,
IhleJ. N.,
JosephD. R.1977; Expression of BALB(X) gp70-like antigens in normal murine tissues in the absence of overt virus expression. Journal of Experimental Medicine 146:422–434
MorseH. C.,
ChusedT. M.,
Boehm-TruittM.,
MatheisonB. J.,
SharrowS. O.,
HartleyJ. W.1979; XenCSA: cell surface antigen related to the major glycoproteins (gp70) of xenotropic murine leukemia viruses. Journal of Immunology 122:443–154
SteffenD. L.,
TaylorB. A.,
WeinbergR. A.1982; Continuing germ line integration of AKV proviruses during the breeding of AKR mice and derivative recombinant inbred strains. Journal of Virology 42:165–175
StephensonJ. R.1980; Type C virus structural and transformation specific proteins. In Molecular Virology of RNA Tumor Viruses pp 245–295 Edited by
StephensonJ. R.
New York: Academic Press;
StrandM.,
AugustJ. T.1973; Structural proteins of oncogenic ribonucleic acid viruses. Interspec II, a new interspecies antigen. Journal of Biological Chemistry 248:5627–5633
TungJ. S.,
VitettaE. S.,
FleissnerE.,
BoyseE. A.1975; Biochemical evidence linking the GIX thymocyte surface antigen to the gp69/71 envelope glycoprotein of murine leukemia virus. Journal of Experimental Medicine 141:198–205