Glucose is a critical product of digestion.

葡萄糖是消化的重要產物。

It is an essential energy source for cellular metabolism.

它是細胞新陳代謝的重要能量來源。

This energy is produced

這種能量的產生

when glucose is used as a substrate for glycolysis

當葡萄糖被用作糖酵解的底物時。

and then the Krebs or Citric Acid Cycle.

然後是克雷布斯或檸檬酸循環。

Following the digestion of food,

跟著食物的消化。

higher levels of glucose circulate through the blood stream

血液中的葡萄糖含量較高。

where it enters different cell types.

在那裡它進入不同的細胞類型。

In muscle cells

在肌肉細胞中

glucose is readily used to produce energy

葡萄糖很容易被用來產生能量。

and is also stored as glycogen,

並以糖原的形式儲存。

a secondary short term energy source.

次要的短期能源。

In fat cells, glucose is used for Triglyceride production,

在脂肪細胞中，葡萄糖用於生產甘油三酯。

and acts as an important energy reserve molecule.

並作為重要的能量儲備分子。

Here we will illustrate the signaling pathway that occurs

在這裡，我們將說明發生的信號轉導途徑。

when glucose is at high levels.

當葡萄糖處於高位時。

This pathway involves multiple proteins and signaling events.

該途徑涉及多種蛋白質和信號傳導事件。

This is termed cytoplasmic signaling.

這被稱為細胞質信號傳導。

Different types of cells

不同類型的細胞

perform similar signaling steps

執行類似的信號傳遞步驟

in response to changes in their environment.

以應對環境的變化。

In the Protein Recycling animation

在蛋白質回收動畫中

we see a group of storage vesicles enriched with GLUT4 proteins

我們看到一組富含GLUT4蛋白的儲存囊泡。

continuously recycling from the cell membrane

不斷從細胞膜上回收

to an inactive location in the cytosol.

到胞漿中的非活性位置。

GLUT4 is a protein that facilitates the movement of glucose into the cell.

GLUT4是一種促進葡萄糖進入細胞的蛋白質。

When high levels of glucose are detected by beta cells in the pancreas,

當胰腺中的β細胞檢測到高水平的葡萄糖時。

insulin is released by the cells.

胰島素是由細胞釋放的。

The insulin circulates through the blood stream

胰島素在血液中循環

until it binds to an insulin receptor embedded in the cell membrane

直到它與嵌入在細胞膜上的胰島素受體結合。

of a muscle, fat, or brain cell.

肌肉、脂肪或腦細胞的。

Once the insulin binds to the receptor,

一旦胰島素與受體結合。

phosphate groups are added

磷酸基團

to the intracellular domain of the receptor.

到受體的胞內域。

Since the receptor itself

由於受體本身

adds the phosphate groups,

增加了磷酸鹽基團。

the process is called autophosphorylation.

這個過程稱為自磷酸化。

This phosphorylation event

這個磷酸化事件

sets off a cascade of molecular events.

引發了一連串的分子事件。

The activated receptor protein

激活的受體蛋白

then adds a phosphate group to another closely associated protein.

然後將一個磷酸基團添加到另一個密切相關的蛋白質上。

This effectively passes the signal from the receptor

這有效地傳遞了來自受體的信號。

to the next step in the signal pathway.

到信號通路的下一步。

Proteins that add phosphate groups to another protein

在另一種蛋白質上添加磷酸基團的蛋白質。

are called kinases.

被稱為激酶。

Kinases are often components of signal pathways,

激酶往往是信號通路的組成部分。

and phosphorylation is an important component

和磷酸化是一個重要的組成部分

in the transmission of a signal from one compartment to another.

在信號從一個車廂傳輸到另一個車廂的過程中，。

In this system,

在這個系統中。

the signal corresponds to the level of blood glucose

信號對應於血糖水準

and is transmitted from outside to inside the cell.

並由外部傳到細胞內部。

Next we see a large pool of molecules that are embedded in the membrane

接下來，我們看到了一大池嵌在膜上的分子。

also being phosphorylated.

也被磷酸化。

Other proteins are then in turn phosphorylated,

然後，其他蛋白質又被磷酸化。

further transmitting the first extracellular signal

進一步傳輸第一胞外信號

that was originally sent from outside the cell membrane.

原本從細胞膜外發出的。

So how does this affect the uptake of glucose?

那麼，這對葡萄糖的攝取有什麼影響呢？

As we mentioned before,

正如我們之前提到的。

Glut4 is a glucose transporter,

Glut4是一種葡萄糖轉運體。

and Glut4 Storage Vesicles are held in a recycling state near the cell membrane.

和Glut4儲存囊泡在細胞膜附近以回收狀態保存。

The vesicles are held mostly in this region

囊泡主要是在這個區域舉行的

because the RAB proteins that interact

因為相互作用的RAB蛋白

with the motor proteins necessary to move the vesicles to the membrane

與運動蛋白一起將囊泡移動到膜上所需的運動蛋白。

are in an inactive state.

處於不活躍狀態。

The final step in the signal pathway

信號通路的最後一步

involves the phosphorylation of a protein

涉及蛋白質的磷酸化

that prevents the RAB proteins from interacting with the vesicles.

阻止RAB蛋白與囊泡相互作用。

When the RAB proteins are no longer inhibited,

當RAB蛋白不再受到抑制時。

the storage vesicles can freely merge with the membrane.

儲存囊泡可以自由與膜合併。

Once the vesicles have merged

一旦囊泡合併

many Glut4 proteins are embedded in the membrane

許多Glut4蛋白被嵌入膜中

and large quantities of glucose can move into the cell.

和大量的葡萄糖可以移動到細胞中。

It is the signaling pathway

它是信號傳導途徑

that insures only the correct molecules will be allowed to enter the target cell.

以確保只有正確的分子才能進入目標細胞。