Cellular phosphorylation is a modification that can change the activity, binding properties, or cellular localization of proteins or enzymes. It is also an important regulatory process that plays a critical role in many disease pathologies, including inflammation, cancer, neurological and metabolic disorders. Enzymes that phosphorylate proteins at specific amino acid residues (e.g., tyrosine, serine, and threonine) are called kinases. Enzymes that remove a phosphate group by hydrolysis are termed phosphatases. Because phosphorylation is central to most signal transduction pathways, phosphorylated peptides (i.e., phosphopeptides) are used for the analysis of protein kinases and phosphatases in may cellular assays.
Chemistry
Phosphoralation may occur on Serine (S, Ser), Threonine (T, Thr) and Tyrosine (Y, Tyr) side chains by phosphoester bond formation. CPC Scientific can synthesize phosphopeptides and incorporate single or multiple combinations of phosphoserine (pS), phosphothreonine (pT), or phosphotyrosine (pY).

Applications
- Studying roles in disease pathologies including cancer, neurodegenerative, and metabolic disorders.
- Developing phospho-specific antibodies.
- Mapping and quantifying phosphorylation sites.
- Developing mass standards for proteomic identification.
- Studying structural PTMs that regulate protein function.
- Developing assays using phosphatase substrates for phosphatase activity.
- Investigating cellular signaling and signal transduction pathways.
Phosphorylated Peptide Citations
Espejo, Alexsandra B., et al. Journal of Biological Chemistry 292.6 (2017): 2255-2265.
"PRMT5pT634 (Biotin-SAIHNPTGRSYpTIGL-COOH, where pT represents phosphothreonine), PGHS2 (Biotin-SGSGVLIKRRSTEL-COOH),PGHS2pT602 (Biotin-SGSGVLIKRRSpTEL-COOH), IRK1 (Biotin-SGSGPRPLRRESEI-COOH), IRK1pS425 (BiotinSGSGPRPLRREpSEI-COOH, where pS represents phosphoserine), ERBB4 (Biotin-GTVLPPPPYRHRNTVV-COOH), and ERBB4pT1306 (Biotin-GTVLPPPPYRHRNpTVV-COOH)) and by CPC Scientific, Inc. (E6 (HPV16) (Biotin-RSSRTRRETQLCOOH) and E6 (HPV16)pT156 (Biotin-RSSRTRREpTQLCOOH))."
Skjevik, Åge Aleksander, et al. Journal of Molecular Biology 426.1 (2014): 150-168.
"The peptides TH-(1-43) (MPTPDATTPQAKGFRRAVSELDAKQAEAIMSPRFIGRRQSLIE) and THp-(1-43) (MPTPDATTPQAKGFRRAVS(PO3)2-ELDAKQAEAIMSPRFIGRRQSLIE) were synthesized by CPC Scientific (San Jose, CA) at approximately 90% purity, as seen by mass spectroscopy, and used without further purification."
Bustad, Helene J., Lars Skjaerven, Ming Ying, Øyvind Halskau, Anne Baumann, David Rodriguez-Larrea, Miguel Costas, Jarl Underhaug, Jose M. Sanchez-Ruiz, and Aurora Martinez. PloS One 7, no. 11 (2012): e49671.
"The peptides TH-(1-43), i.e. MPTPDATTPQAKGFRRAVSELDAKQAEAIMSPRFIGRRQSLIE, and its Ser19-phosphorylated counterpart THp-(1-43), i.e. MPTPDATTPQAKGFRRAVS(PO3)ELDAKQAEAIMSPRFIGRRQSLIE, were synthesized by CPC Scientific (San Jose, CA, USA) at approx. 90% purity, as seen by mass spectroscopy."
Havukainen, Heli, et al. The Journal of Experimental Biology 215.11 (2012): 1837-1846.
"[..] polyserine tract of AmVg and NvVg were synthesized by CPC Scientific (Sunnyvale, CA, USA) for NMR analysis. The synthesis was performed after isotope-labeling expression attempts in Escherichia coli were deemed unsuitable [..] The peptides had the following sequences: AmVg (residues 358–392): EKLKQDILNLRTDISTS(Sp)SS(15I)SSSEENDFWQPKPT AmVg (residues 336–385): R(15V)SKT(15A)MNSNQI(15V)SDNS(15L)-(15S)STEEK(15L)KQDI(15L)N(15L)RTDI(15S)S(15S)(Sp)S(15A)IS (15S)(15S)EEND. NvVg (residues 351–385): EHKHSDESTSE(Sp)FES(15I)ADNNDDSYFQRKPKLTEAP." NvVg (residues 335–372): RPNK(15L)N(15L)QRRHDHKS(15G)EHKHSDE(15S)S-(15S)E(Sp)FE(15A)I(15A)DNNDD.
Leone, Marilisa, et al. Chemical Biology & Drug Design 77.1 (2011): 12-19.
"Cyclo-DEYDDPfK; Cyclo-DE(pY)LDPfK; Cyclo-DE(FCOOH)LDPfK (FCOOH= phenylalanine with a carboxyl group at the para position) were purchased either from the MCW facility of the Wisconsin Medical College or from CPC Scientific (San José, CA, USA)"
Crizer, David M., Yu Xia, and Scott A. McLuckey. Journal of the American Society for Mass Spectrometry 20.9 (2009): 1718-1722.
Phosphopeptide LPISASHpSpSKTR was synthesized by CPC Scientific (San Jose, CA, USA). Both peptides were diluted to a concentration of 20 μM in 49/49/2 (vol/vol/vol) methanol/water/ammonium hydroxide solution."

