Signal sequences

contain one or more positively charged amino acids adjacent to a continuous stretch of 6–12 hydrophobic residues (known as the hydrophobic core)

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#Id: 953

#Unit 5. Developmental Biology

In Strongylocentrotus purpuratus, the acrosome reaction is initiated by a repeating polymer of fucose sulfate.

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#Id: 954

#Unit 5. Developmental Biology

When sulfated polysaccharide binds to its receptor on the sperm, activates 3 sperm membrane proteins: 

(1) A calcium transport channel

(2) A sodium-hydrogen exchanger

(3) A phospholipase enzyme (IP3)

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#Id: 955

#Unit 5. Developmental Biology

Extension of the acrosomal process by the polymerization of G-actin molecules into F-actin by RhoB

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#Id: 956

#Unit 5. Developmental Biology

Acrosomal process have an insoluble, 30,500-Da protein called bindin.

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#Id: 957

#Unit 5. Developmental Biology

Species-specific bindin receptors present on the egg vitelline envelope.

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#Id: 958

#Unit 5. Developmental Biology

Fast block to polyspermy 

Within 1–3 seconds after the binding of the first sperm, the membrane potential shifts from -70mV to about +20 mV