A Cell-Binding, Immunoglobulin-Like Protein from Human Plasma. I. Isolation and Subunit Structure1

Abstract

A protein having Mr of more than 900K (900,000) was isolated by chromatography on a column of Sepharose 4B coupled with solubilized elastin, followed by sucrose density gradient centrifugation. The protein is composed of several disulfide-linked subunits. SDS-polyacrylamide gel electrophoresis and immunoblotting indicated that two of the subunits are identical with the heavy chains of IgM and IgG, and one is immunologically related to the heavy chain of IgA. The results suggested that this protein is a new protein that belongs to the category of, or is closely related to, the immunoglobulins. As described in the succeeding paper, it has cell-binding activity (Fukamizu et al. (1986) J. Biochem. 100, 843-848). We tentatively refer to this protein as "cell-binding immunoglobulin-like protein (CIP)."

Cell-adhesive immunoglobulin M in human plasma

“…The heavy chain was identical with that of IgM (Figure 3C). We have previously reported that this protein might have y-and a-like chains of immunoglobulin in addition to the M-like chain (Ohori et al, 1986). However, it seems that the previous results came from incomplete purification.…”

“…In the previous studies (Ohori et al, 1986;Fukamizu et al, 1986), we described a new adhesive protein from human plasma. It seemed to have a complicated structure containing subunits that are identical with or related to the heavy chains of IgM, IgG, and IgA.…”

“…Preparation of Elastin-Sepharose. Elastin-Sepharose was prepared by coupling the solubilized elastin (a-elastin) with activated CH-Sepharose 4B according to the methods of Ohori et al (1986).…”

“…In the previous study, we found a new cell-binding protein whose molecular weight is higher than 900000 in human plasma (Ohori et al, 1986;Fukamizu et al, 1986). The protein seemed to contain subunits identical with or closely related to heavy chains of immunoglobulins, i.e., the a chain of IgM, the y chain of IgG, and the a chain of IgA.…”

Renal Argininosuccinate Synthetase: Purification, Immunohistochemical Localization, and Elastin-Binding Property

“…[12]. Briefly, elastin from bovine neck ligant was purchased from Sigma Chemical Co. (St. Louis, Mo., USA), and was solubilized by repeat treatments with 0.25 M oxalic acid at 100°C.…”