His tags are the default for most applications — small, minimally interfering and easy to purify by Ni-NTA. Choose Fc when you need dimerisation, added stability or Protein A/G capture; biotin/Avi for directional immobilisation on streptavidin (SPR, BLI, beads); and GST, MBP or SUMO when you need extra solubility or a fusion-based pull-down. Match the tag to your detection and purification strategy rather than the protein itself.

A bioactive protein has been functionally tested — for example, in a cell proliferation, receptor-binding or enzymatic assay — and shown to produce the expected biological effect. Activity data and the assay used are provided on the product datasheet. Bioactivity matters most for cell culture and functional signalling experiments.

It depends on the protein. Mammalian systems (HEK293, CHO) give human-like folding and glycosylation and suit secreted and complex proteins; E. coli is economical and high-yield for smaller, non-glycosylated proteins; insect and yeast systems sit in between. Each product page lists its expression host so you can choose the format appropriate to your assay.

Yes. Many targets are available as human, mouse, rat and other species orthologues so you can work in physiologically relevant models. Use the "Shop by species" links above, or filter within any category by species.

Reconstitute lyophilised proteins in the buffer recommended on the datasheet, add a carrier protein (e.g. 0.1% BSA) for dilute stocks, and aliquot to avoid freeze-thaw cycles. Store as directed — typically −20°C to −80°C for long-term storage. Always check the individual datasheet for target-specific guidance.