Cyclins and cyclin-dependent kinases (cdks) are evolutionarily conserved proteins that are essential for cell-cycle control in eukaryotes. Cyclins (regulatory subunits) bind to cdks (catalytic subunits) to form complexes that regulate the progression of the cell cycle. The main cyclin-cdks complexes formed in vertebrae cells are cyclin-cdks complexes that regulate the progression of the cell cycle. The main cyclin-cdks complexes formed in vertebrae cells are cyclin D-cdk4 (G0/G1), cyclin E-cdk2 (G1/S), cyclin A-cdk2 (S) and cyclin B1-cdk1 (G2/M). These complexes are regulated by activating and inhibitory phosphorylation events, as well as by interactions with small regulatory proteins including p21 and p27[Kip1]. Specific substrates for cdk-cyclin complexes include nuclear lamins, histones, oncogenes (e.g., c-abl and SV40 large T-Ag), tumor suppressor genes (e.g., retinoblastoma protein, Rb) nucleolin and others. Cyclin B1 is a mitotic cyclin complex; expression is normally low in G0/G1, increases in S, and is maximal during G2/M. Cyclin B1 is rapidly degraded at the end of mitosis and is required for cells to exit from mitosis.
GNS-1 recognizes an epitope between amino acids 1-21 of human Cyclin B1. It crossreacts with hamster and mouse cyclin B1. Recombinant human Cyclin B1 was used as immunogen. The antibody was originally characterized by western blot analysis, immunoprecipitation, immunohistochemical staining of acetone-fixed, frozen tissue sections and of formalin-fixed, paraffin-embedded tissue sections, indirect immunofluorescence microscopy of cultured cells and flow cytometry. MOPC-1 is used as a mouse IgG1 isotype (negative) control. The MOPC-21 antibody has unknown specificity. The GNS-1 and MOPC-21 FITC conjugates are matched in F/P ratios. The optimum F/P ratio was experimentally determined by flow cytometric analysis. MOLT4 human leukemia cells (ATCC CRL-1582) are recommended as a positive control for this application.
