DPP-6 (Recombinant)

Frequently Asked Questions

What molecular weight does recombinant DPP-6 run at on SDS-PAGE or Western blot?

The full-length 865-residue DPP-6 polypeptide has a predicted molecular weight of ~97 kDa, but the protein runs noticeably higher on SDS-PAGE — typically 105–115 kDa — due to N-linked glycosylation acquired during expression in HEK293 cells. If you treat the sample with PNGase F prior to electrophoresis, the band collapses toward the ~97 kDa backbone. When using this recombinant as a positive control alongside our matched antibody RP-DPP6, expect a single prominent band in the 105–115 kDa region under reducing conditions.

Which isoforms or processing variants of DPP-6 does this recombinant represent?

This construct (REC-DPP6) encodes the canonical 865-residue human DPP-6 isoform corresponding to UniProt P42658-1. DPP-6 has at least four described splice variants (DPP6-S, DPP6-L, DPP6-K, DPP6-E) that differ at the N-terminal cytoplasmic region; this recombinant represents the long form (DPP6-L), which carries the full intracellular N-terminus. If your experimental model preferentially expresses a shorter isoform, confirm isoform identity of your endogenous target before using this as a WB size reference.

Does recombinant DPP-6 have dipeptidyl aminopeptidase enzymatic activity I can measure in vitro?

No. DPP-6 is catalytically inactive despite its structural homology to prolyl oligopeptidases. The active-site serine that defines the S9B protease family is absent or non-functional in DPP-6, and no measurable dipeptidyl aminopeptidase activity has been detected against standard fluorogenic substrates (e.g., Gly-Pro-AMC or Ala-Pro-AMC). Do not use REC-DPP6 in enzymatic cleavage assays expecting turnover. Its validated research applications are protein–protein interaction studies, Kv4.2 channel trafficking assays, and antibody validation — not peptidase activity profiling.

What assay format and buffer are recommended for DPP-6 Kv4.2 binding or co-immunoprecipitation experiments?

For pull-down or co-IP experiments probing the DPP-6/Kv4.2 (KCND2) interaction, REC-DPP6 performs well in near-physiological buffers: 25–50 mM Tris-HCl pH 7.4, 150 mM NaCl, 0.1% CHAPS or 0.5% n-dodecyl-β-maltoside (DDM) to maintain the transmembrane segment in a soluble, folded state. The standard storage buffer (50 mM Tris-HCl pH 7.5, 150 mM NaCl, 10% glycerol) is compatible as a dilution base. Glycerol concentrations above 5% in the final binding reaction can reduce hydrophobic interaction efficiency; dilute accordingly before adding to detergent-solubilized membrane fractions.

What starting concentration of recombinant DPP-6 is recommended for surface plasmon resonance or bio-layer interferometry binding kinetics?

For SPR or BLI experiments characterizing DPP-6 interactions with Kv4 channel subunits or auxiliary partners, a titration series of 10–500 nM REC-DPP6 is a practical starting range. The protein is supplied at >90% purity by SDS-PAGE, which is generally sufficient for kinetic measurements, but we recommend a size-exclusion polishing step if aggregates affect baseline stability. Running buffer should be matched to the storage buffer minus glycerol (50 mM Tris-HCl pH 7.5, 150 mM NaCl) to minimize bulk refractive index shifts. Regeneration conditions should be optimized empirically; 0.5 M NaCl or mild detergent washes are a reasonable starting point.

Can I use REC-DPP6 as a positive control for Western blot with the RP-DPP6 rabbit polyclonal antibody?

Yes — this is one of the primary design purposes of REC-DPP6. The matched antibody RP-DPP6 (/anti-dpp-6-rabbit-polyclonal-antibody) was raised and validated against the same human DPP-6 sequence expressed in this recombinant, making it a reliable positive control pairing. Load 50–200 ng of REC-DPP6 per lane alongside your cell lysate lanes. Expect a clean band at 105–115 kDa. Running a titration (50, 100, 200 ng) in parallel with lysate lets you confirm antibody linearity and verify that your endogenous band co-migrates with the recombinant standard.

How much recombinant DPP-6 should I load for Western blot to validate a new DPP-6 antibody?

For antibody validation workflows — including confirming specificity of RP-DPP6 or a third-party anti-DPP6 antibody — load a two-point or three-point titration of REC-DPP6: typically 25 ng, 100 ng, and 300 ng per lane. This range brackets the sensitivity of most HRP-conjugated secondary antibody systems and confirms dose-dependent signal. Because REC-DPP6 is >90–95% pure by SDS-PAGE, a single band at ~105–115 kDa with no major cross-reactive species confirms antibody specificity without ambiguity from contaminating proteins present in whole-cell lysates.

How should I store and handle recombinant DPP-6 to maintain integrity across multiple experiments?

REC-DPP6 is supplied in 50 mM Tris-HCl pH 7.5, 150 mM NaCl, 10% glycerol and should be stored at −20°C in single-use aliquots. Repeated freeze-thaw cycles cause aggregation of the transmembrane-containing glycoprotein and should be strictly avoided. Upon first thaw, keep the protein on ice and use within 8 hours. If you need to prepare working dilutions, use the storage buffer as diluent and avoid diluting below ~10 µg/mL in the absence of a carrier protein, as nonspecific adsorption to tube surfaces becomes significant at lower concentrations. Endotoxin is <0.1 EU/µg by LAL assay.