For WB detection of a phosphorylated protein in mouse liver tissue, how should the primary antibody be selected?

When choosing phosphorylation antibodies, don't get stuck on brands first. Clarify the phosphorylation site you need to detect, and prioritize clones that have been validated for that site in mouse liver samples in the literature. CST, Abcam, Merck, and Invitrogen have relatively comprehensive phosphorylation antibody systems, and CST usually clearly labels site specificity. Domestic options such as Abclonal, ZEN, and HuaAn also have candidates, suitable for small-package trials first. Before ordering, ask the sales representative to send validation images, focusing on whether there are phosphorylated/non-phosphorylated peptide controls and whether a single target band is detected. Small packages can be purchased for under 500 per unit, but large packages may exceed that, so try before stockpiling.

There is no need to memorize dilution ratios. Perform a gradient at 1:500–1:2000 according to the instructions. If background is high, prioritize reducing the primary antibody concentration and incubating overnight at 4°C. For mouse liver tissue lysate, be sure to add sufficient phosphatase inhibitors during lysis; otherwise, phosphorylation signals are prone to drop. For blocking, use 5% BSA or the manufacturer-recommended blocking solution. Wash membranes with TBST, adding 0.1% Tween-20 if necessary. If a domestic primary antibody gives high background, first confirm whether the total protein loading amount is too high or the exposure time is too long; these affect background more than changing brands. Membrane strips can be pre-adsorbed, but this increases workload.

Within 500 RMB per vial, you can choose domestic brands or small-pack imported antibodies. The price of CST phospho-antibody small packs generally falls near this range as well, but popular targets sometimes exceed the budget. For Shanghai stock, you can ask UniV, Dakewe, GeneTech, Shanghai Qianchen, Aoji, etc. Before ordering, have the sales rep confirm the Shanghai warehouse or cold-chain transit time; a webpage showing in-stock does not mean it can ship the same day. If urgently needed, prioritize local ordering for self-pickup or SF Express cold chain to avoid repeated freeze-thaw cycles of the antibody.

When comparing suppliers, beyond unit price, ask whether they can provide original manufacturer validation images, whether they support non-specific returns or exchanges, and their trial sample policy. Some domestic brands can first send 5-10 μL trial samples, and you can buy the full package if suitable; imported brands generally have more complete technical support and data, but are more expensive. Don't just look at claims of "high specificity"; look at validation using mouse liver tissue, because the liver's high metabolic background and blood residue can affect phosphorylated antibody performance.

To judge whether a primary antibody is good, it is recommended to perform phosphorylation-specific validation: take part of the lysate and treat it with λ-PPase, then compare whether the target band disappears or weakens before and after treatment; a peptide competition assay is even better. Also check whether the molecular weight matches the expected target protein, and if necessary, use a total protein antibody for parallel bands to prove that it is not a difference in loading amount. If funding is limited, first apply for a trial size or borrow a small package from another lab to run one membrane, and do not buy a large size right away.