The sequence 130-137 of human interferon-alpha 2 is involved in the competition of interferon, prothymosin alpha and cholera toxin B subunit for common receptors on human fibroblasts.
125I-labelled recombinant human interferon alpha 2 (rHuIFN-alpha 2) capable of high-affinity binding (Kd = 2.46 +/- 0.18 x 10(-10) M) with receptors expressed on mouse thymocytes was obtained. Prothymosin alpha (proTM-alpha) but not cholera toxin was found to compete with radiolabelled IFN-alpha 2 for binding to the same receptor (Ki = 3.68 +/- 0.21 x 10(-11) M). The synthetic peptide covering the sequence 130-137 of IFN-alpha 2 (authors' definition: alpha-peptoferon) was shown to have the capacity to displace the labelled IFN-alpha 2 from the IFN-alpha 2/receptor complex (Ki = 7.19 +/- 0.12 x 10(-11) M). It was shown that receptors of this type are localized in plasmatic membrane fraction. Using [125I]-alpha-peptoferon, specific and saturable binding was detected on human fibroblasts and the data fitted a single binding site. Scatchard analysis yielded a Kd of 9.63 +/- 0.17 x 10(-8) M. The binding was competitively inhibited by IFN-alpha 2 (the Ki value in competition assays was 1.37 +/- 0.12 x 10(-8) M), proTM-alpha(Ki = 2.2 +/- 0.2 x 10(-7) M) and cholera toxin B subunit (Ki = 5.5 +/- 0.2 x 10(-7)). The present study has demonstrated that the sequence 130-137 of HuIFN-alpha 2 is involved in the competition of HuIFN-alpha 2, proTM-alpha and cholera toxin B subunit for common receptors on human fibroblasts.
Zav'Yalov
V P
VP
Institute of Immunology, Lyubuchany, Chekhov District, Moscow Region, Russia.
Navolotskaya
E V
EV
Vasilenko
R N
RN
Abramov
V M
VM
Volodina
E Y
EY
Roslovtseva
O A
OA
Prusakov
A N
AN
Kaurov
O A
OA
D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D002772:Cholera Toxin / Q000378:metabolism; D005347:Fibroblasts; D006801:Humans; D016898:Interferon-alpha / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D008808:Mice, Inbred CBA; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013947:Thymosin / Q000031:analogs & derivatives / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology
D016898:Interferon-alpha; D010455:Peptides; D011498:Protein Precursors; D011956:Receptors, Cell Surface; C040782:prothymosin alpha; D013947:Thymosin; D002772:Cholera Toxin