B7-33 is a synthetically produced single-chain peptide derived from structural regions of the H2-relaxin protein. In laboratory research settings, B7-33 is utilized as a selective molecular probe for investigating relaxin receptor signaling bias, extracellular matrix regulation, and receptor-mediated kinase pathway activation in cellular and animal model systems.

Unlike full-length relaxin peptides, B7-33 exhibits altered receptor signaling profiles that allow researchers to examine downstream pathway selectivity without broad second-messenger activation. All descriptions herein are limited strictly to mechanistic and preclinical research contexts.

Sequence: VIKLSGRELVRAQIAISGMSTWSKRSL
PubChem CID: 318164840
Synonyms: (B7-33)H2, GTPL9321

Source: Chemical Science

B7-33 is employed in research environments to study receptor-biased signaling at the relaxin family peptide receptor 1 (RXFP1). Experimental use focuses on quantifying kinase activation profiles, extracellular matrix turnover markers, and receptor heterodimerization behavior using molecular, cellular, and histological assays.

Additional applications include evaluation of peptide-mediated modulation of matrix metalloproteinase expression, collagen organization, and signaling pathway selectivity in in-vitro systems and in-vivo animal models.

B7-33 demonstrates preferential activation of extracellular signal-regulated kinase (ERK1/2) signaling following RXFP1 receptor engagement, with minimal activation of cyclic AMP–dependent pathways. This signaling bias enables targeted examination of kinase-driven transcriptional and post-translational responses.

Mechanistic studies indicate that RXFP1 activation by B7-33 facilitates receptor interaction with angiotensin II type-2 receptors, contributing to downstream modulation of matrix-associated signaling networks. These interactions are assessed using phosphorylation assays, gene expression profiling, and extracellular matrix component analysis.

In preclinical animal and cellular studies, B7-33 has been investigated for its effects on extracellular matrix composition, metalloproteinase regulation, and vascular signaling endpoints. Experimental outcomes are measured using histological staining, biochemical quantification, and receptor signaling assays.

Additional research explores the incorporation of B7-33 into biomaterial coatings to evaluate cellular responses to implanted substrates, focusing on matrix deposition and capsule formation in controlled experimental systems.

B7-33 is supplied as a synthetic research peptide intended for laboratory use only. Identity and purity are verified using analytical techniques such as high-performance liquid chromatography (HPLC) and mass spectrometry (MS).

This material is not formulated for diagnostic, medical, veterinary, or clinical application.

The above literature was researched, edited and organized by Dr. E. Logan, M.D. Dr. E. Logan holds a doctorate degree from Case Western Reserve University School of Medicine and a B.S. in molecular biology.

Dr. Hossain is being referenced as one of the leading scientists involved in the research and development of B7-33. In no way is this doctor/scientist endorsing or advocating the purchase, sale, or use of this product for any reason. There is no affiliation or relationship, implied or otherwise, between Peptide Sciences and this doctor.

1. R. J. Summers, “Recent progress in the understanding of relaxin family peptides and their receptors,” Br. J. Pharmacol., vol. 174, no. 10, pp. 915–920, 2017, doi: 10.1111/bph.13778.
2. “RXFP1 Gene – GeneCards | RXFP1 Protein | RXFP1 Antibody.” [Online]. Available: https://www.genecards.org/cgi-bin/carddisp.pl?gene=RXFP1. [Accessed: 18-Mar-2020].
3. “RXFP2 Gene – GeneCards | RXFP2 Protein | RXFP2 Antibody.” [Online]. Available: https://www.genecards.org/cgi-bin/carddisp.pl?gene=RXFP2. [Accessed: 18-Mar-2020].
4. “RXFP3 Gene – GeneCards | RL3R1 Protein | RL3R1 Antibody.” [Online]. Available: https://www.genecards.org/cgi-bin/carddisp.pl?gene=RXFP3. [Accessed: 18-Mar-2020].
5. J. Grosse et al., “Insulin-like peptide 5 is an orexigenic gastrointestinal hormone,” Proc. Natl. Acad. Sci., vol. 111, no. 30, pp. 11133–11138, Jul. 2014, doi: 10.1073/pnas.1411413111.
6. M. A. Hossain et al., “A single-chain derivative of the relaxin hormone is a functionally selective agonist of the G protein-coupled receptor, RXFP1,” Chem. Sci., vol. 7, no. 6, pp. 3805–3819, 2016, doi: 10.1039/C5SC04754D.
7. J. D. Silvertown, J. Ng, T. Sato, A. J. Summerlee, and J. A. Medin, “H2 relaxin overexpression increases in vivo prostate xenograft tumor growth and angiogenesis,” Int. J. Cancer, vol. 118, no. 1, pp. 62–73, Jan. 2006, doi: 10.1002/ijc.21288.
8. S. Feng et al., “Relaxin promotes prostate cancer progression,” Clin. Cancer Res. Off. J. Am. Assoc. Cancer Res., vol. 13, no. 6, pp. 1695–1702, Mar. 2007, doi: 10.1158/1078-0432.CCR-06-2492.
9. S. A. Marshall et al., “B7-33 replicates the vasoprotective functions of human relaxin-2 (serelaxin),” Eur. J. Pharmacol., vol. 807, pp. 190–197, Jul. 2017, doi: 10.1016/j.ejphar.2017.05.005.
10. Afroze Syeda H et al., “Abstract P3042: Novel Peptide B7-33 and It’s Lipidated Derivative Protect Cytotrophoblasts From Preeclampsia Phenotype in a Cellular Model of the Syndrome,” Hypertension, vol. 74, no. Suppl_1, pp. AP3042–AP3042, Sep. 2019, doi: 10.1161/hyp.74.suppl_1.P3042.
11. “Coatings Releasing the Relaxin Peptide Analogue B7-33 Reduce Fibrotic Encapsulation | Request PDF.” [Online]. Available: https://www.researchgate.net/publication/337205944_Coatings_Releasing_the_Relaxin_Peptide_Analogue_B7-33_Reduce_Fibrotic_Encapsulation. [Accessed: 19-Mar-2020].

ALL ARTICLES AND PRODUCT INFORMATION PROVIDED ON THIS WEBSITE ARE FOR INFORMATONAL AND EDUCATIONAL PURPOSES ONLY.

The products offered on this website are furnished for in-vitro studies only. In-vitro studies (Latin: in glass) are performed outside of the body.  These products are not medicines or drugs and have not been approved by the FDA to prevent, treat or cure any medical condition, ailment or disease.  Bodily introduction of any kind into humans or animals is strictly forbidden by law.

For Laboratory Research Only. Not for human use, medical use, diagnostic use, or veterinary use.