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The identification of a naturally occurring cell surface growth inhibitor related to a previously described bovine sialoglycopeptide
Author(s) -
Fattaey Heideh K.,
Enebo Daniel J.,
Moos Philip J.,
Johnson Terry C.
Publication year - 1993
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240520110
Subject(s) - sialoglycoprotein , biochemistry , membrane , isoelectric point , isoelectric focusing , incubation , biology , lectin , cell membrane , chromatofocusing , pmsf , affinity chromatography , protein subunit , chemistry , microbiology and biotechnology , enzyme , gene
Abstract A 66‐kDa sialoglycoprotein has been identified as the parental membrane molecule of an earlier described sialoglycopeptide (SGP), an 18‐kDa molecule released by protease treatment of intact bovine cerebral cortex cells that was shown to be a potent inhibitor of cellular proliferation. The 66‐kDa parental sialoglycoprotein (p‐SGP) was purified approximately 2,400‐fold, to apparent homogeneity, from bovine cerebral cortex cell membranes by its release during incubation with 3 M NaCl, preparative isolelectric focusing and lectin affinity chromatography. Although a membrane‐associated molecule, the p‐SGP appeared to be tightly bound to the cell membrane, since it was not released during incubations in the absence of 3 M NaCl. Incubation of the membrane preparations with 3 M urea proved to be too harsh, and the antigenicity required to follow the purification of the p‐SGP was abolished. Analyses by SDS–PAGE, under reducing and nonreducing conditions, suggested that the p‐SGP membrane component was a single polypeptide without subunit structure. The p‐SGP was shown to be structurally related to the SGP fragment by immunoblots with IgG raised to the SGP inhibitor, and functionally related to the SGP by its ability to inhibit Swiss 3T3 proliferation at concentrations strikingly similar to that previous measured with the SGP fragment.