Define ionophore and describe how the compound A23187 affect

Define ionophore and describe how the compound A23187 affects intracellular Ca2+ levels in sperm and the capacitation process.

Solution

Ionophore are small hydrophobic lipid soluble molecule that disolve in lipid biolayer and increase their permeability to specific inorganic ions . Ionophores shield the charge of the ions to be transported, enabling it to penetrate the hydrophobic interior of the lipid bilayer. there are two kind of ionophores.

1. Mobile ion channels It transports the K+ ions down its electrochemical gradient eg.(Valinomycin )

2. channel formers - In membrane it form channel. the channel permits the passage of water and univalent cations but not anions eg. (gramisidin).

The molecule metioned in the question is a Protein-Tyrosine Kinase (HCK) which involves in various signaling events capacitation is also one of them.The capacitation depends on PKA activation mediated by the Ca²⁺ and HCO₃-dependent soluble adenylyl cyclase. It has been suggested that Ca²⁺ is transported into the cell by the sperm-specific Ca²⁺ channel (CatSper) and HCO₃ by the Na⁺/HCO₃ cotransporter.