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Isolation and purification of the IGF-I protein complex from rabbit seminal plasma: Effects on sperm motility and
A Minelli1, M Moroni, C Castellini
1Dipartimento di Scienze Biochimiche e Biotecnologie Molecolari, Sezione di Biochimica Cellulare, Perugia 06123, Italy. albami@tin.it
Abstract:
A protein of about 150 kDa affecting sperm kinetic motility and viability was purified from rabbit seminal plasma. The incubation of rabbit sperm with this purified seminal plasma protein caused significant changes in sperm viability and motility. Moreover, the seminal protein showed a noticeable reactivating effect on immotile spermatozoa. A 10-mg amount of purified protein, added to immotile rabbit spermatozoa suspended in Tris-citrate, pH 7.4, resulted in a 48% reactivation. It is known that circulating insulin-like growth factors are bound to specific high-affinity binding proteins and form complexes with relative molecular masses of about 150 kDa. Western blotting analyses proved the existence of insulin-like growth factor in the protein purified from rabbit seminal plasma and immunofluorescence staining showed the existence of IGF-1 receptor in rabbit spermatozoa. Therefore, we suggest that the purified rabbit seminal plasma protein may represent the protein complex delivering IGF to the sperm cells thus affecting their physiological functions.
Insights
A novel seminal plasma protein was purified from rabbits, significantly improving sperm motility and viability. This protein complex may deliver insulin-like growth factor (IGF) to sperm, enhancing their function.
Area of Science:
- Reproductive Biology
- Biochemistry
- Andrology
Background:
- Spermatozoa motility and viability are crucial for reproductive success.
- Seminal plasma contains various proteins that influence sperm function.
- Insulin-like growth factors (IGFs) are known to play roles in cell growth and differentiation.
Purpose of the Study:
- To purify and characterize a protein from rabbit seminal plasma that affects sperm kinetic motility and viability.
- To investigate the potential role of this protein in sperm reactivation.
- To identify the nature of the purified protein and its interaction with sperm.
Main Methods:
- Purification of a ~150 kDa protein from rabbit seminal plasma.
- Incubation of rabbit sperm with the purified protein.
- Assessment of sperm viability and motility.
- Western blotting to detect insulin-like growth factor (IGF).
- Immunofluorescence staining for IGF-1 receptor on spermatozoa.
Main Results:
- A ~150 kDa protein was purified from rabbit seminal plasma.
- Incubation with this protein significantly altered sperm viability and motility.
- The purified protein demonstrated a 48% reactivation of immotile spermatozoa.
- Western blotting confirmed the presence of IGF in the purified protein.
- Immunofluorescence showed IGF-1 receptors on rabbit spermatozoa.
Conclusions:
- The purified rabbit seminal plasma protein, approximately 150 kDa, significantly impacts sperm motility and viability.
- This protein exhibits a notable reactivating effect on immotile spermatozoa.
- The protein complex likely delivers insulin-like growth factor (IGF) to sperm cells, influencing their physiological functions.
