Membrane ion channels that play important roles in generation of the action potential:

T (transient) channels 

L (long-lasting) channels Voltage gated potassium ion channel

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Two major mechanisms during fertilization in sea urchin:

Species-specific sperm attraction 

Species-specific sperm activation

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Chemotaxis 

sperms are attracted toward eggs of their species by following a gradient of a chemical secreted by the egg.

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In Sea urchin,

Sperm-activating peptides provide direction to sperm during chemotaxis.

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SAP in the egg jelly of the sea urchin Arbacia punctulata 

Resact (14-amino acid chemotactic peptide)

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SAP in the egg jelly of, Strongylocentrotus purpuratus

Speract

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Resact from Arbacia egg jelly binds to its receptor on the sperm, activates the receptor’s guanylyl cyclase (RGC) activity.