• Cargo: Residues 57 to 95 of human p53 isoform a
• Domain type: Transactivation domain (MDM2 binding)
• 39 Amino acids
Comment: the P to R change from the consensus sequence (highlighted) is a known polymorphism which has been linked to Cancer susceptibility.
Reference: p53 codon 72 polymorphism and the risk of lung cancer in a Korean population. Piao JM, Kim HN, Song HR, Kweon SS, Choi JS, Yun WJ, Kim YC, Oh IJ, Kim KS, Shin MH. Lung Cancer. 2011;73(3):264–7. doi:10.1016/j.lungcan.2010.12.017. PMID 21316118.
• Molecular weight (daltons): 11423
• Isoelectric point (pI): 8.86
• Extinction Coefficient (A280 reduced) : 12490
• Solubility : >200 micromolar
• Purity: Runs anomalously 80% see comment
• Cell-Permeation : Passes
• 1 Unit = 10 nanomoles = 0.114 mg
Comment: p53’s mass is actually only 43.7 kD but it runs as a 53-kilodalton (kD) protein on SDS-PAGE. This difference is due to the high number of proline residues in the protein, which slows its migration on SDS-PAGE, thus making it appear heavier than it actually is (1). This effect is observed with p53 from a variety of species, including humans, rodents, frogs, and fish, and we believe it is the reason for the anomalous migration pattern seen in out laboratory.
Reference. Cell-free translations of proline-rich protein mRNAs. Ziemer MA, Mason A, Carlson DM. J Biol Chem. 1982 Sep 25;257(18):11176-80.
Cupid-p53-B Peptide Data:
Cell permeating Cupid p53 peptide BA. Purified Cupid-p53-B peptide was subjected to SDS-PAGE alongside a prestained molecular marker ladder. The gel was then stained for protein with a commercial coomassie-based stain.
M = Weight markers shown in kD
S = Cupid-p53-B peptide sample. The protein runs anomalously appearing at 18-20 kD.
Cell permeating Cupid
p53 peptide B
B. Cupid-p53-B peptide labelled with fluorescein was subjected to SDS-PAGE and observed with a blue light transilluminator.
M = Weight markers shown in Kd, S = Labelled Cupid-p53-B peptide sample.
C. Labelled peptide was incubated with living cells at 10 micromolar for 60 minutes before exchanging the media and washing the cells. Cells were imaged using a fluorescence microscope with filter sets for Fluorescein (Upper Panel) or phase contrast (Lower Panel). Fluorescent images of treated cells are taken at a setting where the background (autofluorescence) of the untreated cells is at the threshold of detection. We observe the peptide fluorescence distributed diffusely throughout all cells.