An RGD tumor-targeting peptide, which binds to αvβ3 receptors. It can be easily conjugated to fluorophore tags, chelators, or carriers. Palecek et al. converted the ε-amino group into the azide by diazo transfer allowing further functionalization by click chemistry. Mercapto groups can be introduced via acylation of this peptide with S-acetylthio-acetic acid (SATA).

Melanotan II, a cyclic MSH analog, is a potent full agonist of the melanocortin-3 and melanocortin-4 receptors (MC3-R and MC4-R). Intracerebroventricular administration of MTII inhibited feeding in four different mouse models of hyperphagia. MTII is a valuable tool for the study of the agouti obesity syndrome and of the role of melanocortinergic neurons in feeding.

This peptide corresponds to residues 317 to 320 of the oncogenic protein Shc. Similar phosphotyrosine motifs are also found in receptor tyrosine kinases and substrates of them. This peptide binds with high affinity (18 nM) to the SH2 domain of the growth factor bound-2 protein (Grb2). It is a useful inhibitor of the interaction of Grb2 with Shc, or with other Grb-2-binding proteins involved in the cell signaling cascade.

The small mammalian heat shock proteins show a highly conserved amino acid sequence and are suggested to play a major role in the increased thermal resistance acquired by cells after exposure to heat shock. They possess two major sites of phosphorylation which are each located in the conserved protein kinase phosphorylation site motif Arg-X-X-Ser. The above-mentioned phosphopeptide, which contains the second site of phosphorylation, has been isolated from a tryptic digest of phosphorylated native and recombinant mouse hsp 25. Only Ser86, the first of the three serine residues is phosphorylated.

Stapled peptide is a full-carbon scaffold with an α-helical structure. The all-carbon scaffold stabilizes the α-helical structure, enhances the interaction between the peptide molecule and the protein, and the peptide can pass through the cell membrane and is not easily hydrolyzed. Stapled peptides have higher physiological activity than previous small molecule drugs and protein analogs.

TSRHK-K(Me)-LMFKT peptide is derived from amino acid residues 377-387 of human p53 tumor suppressor protein, with monomethylation at Lys382. Methylation of p53 at Lys382 inhibits expression of p53 target genes and decreases apoptotic and cell cycle arrest functions of p53. This allows p53-dependent DNA repair without apoptosis. Levels of this peptide decrease in response to DNA damage.