Domain

Domains are formed by combinations of SS, SSS, motifs and connected by loops and turns.

Highly conversed and may be common in most unrelated proteins

They evolve

Can function Independently

Average 100 amino acids 

Single hydrophobic core

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#Id: 7593

#Unit 5. Developmental Biology

The capacitated sperm are also able to detect and respond to picomolar amounts of the hormone progesterone, which is secreted by the cumulus cells surrounding the egg

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#Unit 5. Developmental Biology

Chemotaxis oocyte and its accompanying cumulus cells secrete molecules that attract capacitated sperm toward the egg during the last stages of sperm migration

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#Unit 5. Developmental Biology

Chemotactic compounds hormone Progesterone,  made by the cumulus cells, might trigger the release of Protein kinase A from the sperm cell membrane, & allowing it to activate the sperm-specific cation CatSper channels would facilitate the transfer of calcium ions into the sperm, where they would cause exocytosis of the acrosome

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#Unit 5. Developmental Biology

Mouse cumulus cells also secrete a substance, CRISP1, that attracts sperm and hyperactivates them through CatSper channels

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#Id: 7597

#Unit 5. Developmental Biology

The zona pellucida in mammals plays a role analogous to that of the vitelline envelope in invertebrates; the zona, however, is a far thicker and denser structure than the vitelline envelope

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#Id: 7598

#Unit 5. Developmental Biology

The mouse zona pellucida is made of three major glycoproteins—ZP1, ZP2, and ZP3