B7-33

H2-relaxin is a naturally occurring, endogenous protein compound, which was synthetically mimicked and named the “B7-33” peptide. The H2-relaxin protein class comprises relaxin, H3-relaxin, insulin-like peptide-3, and insulin-like peptide-5. All these proteins have been suggested to exhibit a variety of biological actions, including possibly affecting genetic functions and the reproductive, musculoskeletal, and cardiovascular systems.⁽²⁾ Considered structurally similar to H2-relaxin, the synthetic equivalent B7-33 may possess anti-fibrotic potential.

There are four different receptors that these naturally produced relaxin proteins are speculated to bind with, namely RXFP-1, RXFP-2, RXFP-3, and RXFP-4. Each receptor has a different action, as outlined below:⁽²⁾

• RXFP-1 receptor is suggested to influence sperm motility
• RXFP-2 receptor appears to impact testicular development
• RXFP-3 receptor may play a role in circadian rhythm and sleep cycle regulation
• RXFP-4 receptor has shown indications of affecting hunger hormone signaling cycles

Due to the variety of receptors involved and a wide range of biological impact, extensive research has been conducted on the relaxin protein and its analogs, such as the B7-33 peptide, to fully understand their potential.