Name: 激素如何使用G蛋白信號通路。基礎知識視頻回顧。 (How Hormones Use G-protein Signaling Pathways: A Video Review of the Basics.)
Uploaded: 2021-01-14T06:03:59.000Z
Duration: 9 min 50 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

Hormones are constantly floating through our

At any given point in time you may have growth

luteinizing hormones coursing through your

circulation. Some of these hormones, such as

the steroid hormones, can pass directly into

cells and bind to intracellular receptors.

Others, such as protein and peptide hormones

are hydrophilic, and must bind to receptors in

This brings up an important point: How does the

extracellular signal of a hormone get transmitted

This is commonly accomplished using second

messengers: small molecules such as cAMP or

Second messengers relay information from the

first “messenger,” the hormone, into the cell.

These second messengers are often produced

using common proteins associated with the

G-proteins are “coupled” to receptors in the

plasma membrane of the cell. G-protein coupled

receptors can mediate the responses to signals

Many different types of ligands can activate G-

proteins such as fatty acids, proteins, peptides,

Interestingly, about half of all known drugs work

Let’s take a closer look at how G-protein

signaling mechanisms work. Hormones floating

through the bloodstream may circulate freely or

In the bloodstream, the hormone dissociates

from any associated binding proteins and moves

out of the capillary and into the interstitial fluid.

The hormone then binds to a hormone receptor

The hormone receptor is associated with a G-

protein, as shown here, which is attached to the

The G-protein is responsible for relaying the

hormonal information to downstream signaling

Each type of G-protein is specific for one of

G-proteins have 3 subunits: an alpha-subunit, a

When the G-protein is in an inactive state, the

The binding of the hormone to the G-protein

coupled receptor initiates a conformational

This stimulates the alpha subunit of the G-

protein to exchange its bound GDP for a GTP.

the G-protein is in an active state. The activated

G-protein dissociates into the alpha subunit, and

The actual target of the activated subunit

depends on the G-protein that is activated.

In this video, we will first examine the pathway is

The G-protein in this case is a stimulatory

The activated alpha-subunit of GS binds to the