Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.2.1.7 (BAL)
 1,977 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Binding of cyclic AMP (cAMP) to the cell surface receptor induces a transient activation of guanylate cyclase in Dictyostelium discoideum. A frigid mutant (HC85) which lacks G alpha 2, a guanine nucleotide binding protein, does not respond to cAMP. We found that 2,3-dimercapto-1-propanol (BAL) induced a continuous activation both in the frigid and in its parents. Therefore, the BAL-induced continuous activation of guanylate cyclase is independent of G alpha 2. We also found that cAMP enhanced the BAL-induced continuous activation in the frigid mutant. This result suggests that an unidentified signal transduction mechanism from the cAMP-receptor besides the one involving G alpha 2 plays a role in the enhancement of activation. Lastly, we found that the BAL-induced continuous activation was terminated by cAMP in the parental strain, but not in the frigid mutant. Therefore, the cAMP-induced suppression on the BAL-induced continuous activation is mediated through G alpha 2.
 ...
PMID:Regulation of guanylate cyclase by a guanine nucleotide binding protein, G alpha 2, in Dictyostelium discoideum. 167 66

T cell-replacing factor (TRF)/IL-5 is a glycosylated polypeptide that acts as a key factor for B cell growth and differentiation. Since IL-5 action is probably mediated by specific cell surface receptor(s), we have characterized the binding of IL-5 to cells using biosynthetically [35S]methionine-labeled IL-5 and 125I-IL-5 that had been prepared using Bolton-Hunter reagent. The radiolabeled IL-5 binds specifically to BCL1-B20 (in vitro line) (a murine chronic B cell leukemic cell line previously shown to differentiate into IgM-secreting cells in response to IL-5) within 10 min at 37 degrees C. There are two classes of binding sites with high affinity (Kd = 66 pM) and low affinity (Kd = 12 nM) for IL-5 and an average number of binding sites for high affinity and for low affinity were 400 and 7,500 per cell, respectively. The specificity of binding of radiolabeled IL-5 has been confirmed by demonstrating that only unlabeled IL-5 and anti-IL-5 mAb but not by IL-1, IL-2, IL-3, IFN-gamma, and GM-CSF inhibit radiolabeled IL-5 binding to BCL1-B20 cells. Treatment of surface-bound radiolabeled IL-5 with bivalent crosslinkers identified a membrane polypeptide of Mr 46,500 to which IL-5 is crosslinked. A variety of cell types have been surveyed for the capacity to bind specifically radiolabeled IL-5 with high affinity. BCL1 cells MOPC104E (murine myeloma cell line) expressed IL-5-R, whereas BAL. 17 and L10 A (B cell lymphoma) did not. T cell line, mastocytoma cell line, or macrophage tumor cell line did not display detectable levels of IL-5-R. were hardly detectable on normal resting B cells but were expressed on LPS-activated B cells, fitting the function of IL-5 that acts on activated B cells for their differentiation into Ig-secreting cells. Intriguingly, early B cell lines (J-87 and T-88) that grow in the presence of IL-5 expressed significant but low numbers of high-affinity binding sites for IL-5. The biological effects of IL-5 were mediated by high-affinity binding sites. The identification and characterization of IL-5-R should provide new insight into the apparent diverse biological activities of IL-5.
 ...
PMID:Receptors for T cell-replacing factor/interleukin 5. Specificity, quantitation, and its implication. 326 7