The Purified ~55 Kda Uterovaginal Lizard Protein Retards Sperm Motility In A Diverse Group Of Vertebrates

Sperm storage in female invertebrates and vertebrates is a fascinating aspect of reproductive success across animal phyla, yet the underlying mechanisms remain largely elusive. Using the Indian Garden lizard (Calotes versicolor) as a model organism, we previously identified and sequenced an abundant yet unique ~55 kDa protein from uterovaginal junction (UVJ) flushings without any homology to protein databases. Characterizing this protein exhibited retardation of lizard sperm motility in a concentration- and time-dependent manner [1]. The present study demonstrates that this protein exhibits similar inhibitory effects on sperm from mice, rats, and humans without compromising viability. These results suggest that the ~55 kDa protein has significant potential for applications in prolonging sperm survival even in heterologous sperm and has the potential to assist endangered species conservation.