Axolinin localization in the nervous tissue of squid revealed by monoclonal antibodies specific for axolinin: characterization of monoclonal antibodies against axolinin

Construction of ELISA system to quantify human ST2 protein in sera of patients

The human ST2 gene can be specifically induced by growth stimulation in fibroblastic cells, and can also be induced by antigen stimulation in Th2 cells. The gene encodes a soluble secreted protein, ST2, and a transmembrane protein, ST2L, which are closely related to the interleukin-1 receptor. To gain insight into the biological roles of the ST2 gene, three monoclonal antibodies (MAbs) against human ST2 gene products were obtained. To obtain these antibodies, immunization was carried out using two different immunogens: purified soluble human ST2 protein (hST2), and COS7 cells, which express the extracellular portion of human ST2L. 2A5 and FB9 MAbs were derived from the immunization with soluble hST2, and HB12 was derived from the COS7 cell immunization. All three antibodies were shown to detect native forms of the human ST2 gene products by immunoprecipitation, flow cytometry, and enzyme-linked immunosorbent assay (ELISA). In the competitive ELISA using biotinylated and nonlabelled MAbs, neither FB9 nor HB12 affected the binding of 2A5 to ST2 gene products. Based on this result, we constructed a sandwich ELISA system using 2A5 and FB9 to measure the concentration of soluble hST2 in sera. The ELISA, combined with the flow cytometry using these antibodies, will be a useful tool for elucidating the functions of human ST2 gene products in individuals.

Studies on natural ST2 gene products in the human leukemic cell line UT-7 using monoclonal antihuman ST2 antibodies

Eight species of murine monoclonal antibodies against human ST2 protein, which is highly similar in protein sequence to the interleukin 1 receptor, were produced. The fusion was carried out between the murine myeloma cell line PAI and murine lymph node or spleen cells from mice immunized with the recombinant ST2 protein produced in Escherichia coli. Characterization of these monoclonal antibodies by immunoblot analysis revealed that they all reacted with recombinant, N-glycosylated ST2 protein that was secreted from COS7 cells transiently transfected with a mammalian expression vector carrying ST2 cDNA. The recombinant N-glycosylated ST2 protein could be immunoprecipitated by 5 out of 6 species of the IgG class monoclonal antibodies. Furthermore, these antibodies were also able to detect, by immunofluorescence, the membrane-bound chimeric molecule possessing an extracellular portion of human ST2 and a transmembrane and cytoplasmic portion of murine receptor type ST2L expressed on COS7 cells, indicating that these monoclonal antibodies were useful for detecting the natural membrane-bound ST2 in human cells. Combining immunoprecipitation and immunofluorescence with the aid of these monoclonal antibodies, together with the reverse transcriptase-polymerase chain reaction method, the human leukemic cell line UT-7 was demonstrated to express human ST2 mRNA and protein. The identification of the ST2 gene product in UT-7 cells may help investigators elucidate the function of the human ST2 gene.

Selective purification of microtubule-associated proteins 1 and 2 from rat brain using poly(L-aspartic acid)

A rapid and selective purification procedure for microtubule-associated protein (MAP) 1 and MAP 2 has been established. This procedure is based upon the fact that poly(L-aspartic acid) (PLAA) can specifically remove MAP 1 from microtubules polymerized by taxol (Nakamura et al., 1989, J. Biochem. 106, 93-97). MAP 1 released by PLAA was further purified by column chromatography on phosphocellulose and Bio-Gel A-15m. The purified MAP 1 contained MAPs 1A and 1 B. From microtubules devoid of MAP 1, MAP 2, consisting of MAPs 2A and 2B, could also be isolated by exposure to high ionic strength solutions in the presence of taxol without heat treatment. Both MAPs 1 and 2 cosedimented with microtubules consisting of purified tubulin.