A protein such as epidermal growth factor (EGF) is MOST LIKELY to:

Question

BlackTom AI · Accepted Answer

EGF is a peptide growth factor that acts at the cell surface by binding to receptor tyrosine kinases (RTKs). Binding of EGF to the extracellular portion of the epidermal growth factor receptor (EGFR) induces receptor dimerization, activation of the receptor's intrinsic tyrosine kinase activity, and subsequent autophosphorylation on tyrosine residues of the receptor. These phosphotyrosines serve as docking sites for adaptor proteins (with SH2/PTB domains), which trigger downstream rapid signalling cascades (e.g., RAS–MAPK, PI3K–AKT) that alter gene expression and cell behaviour.

Step-by-step reasoning:
1. EGF is a water-soluble protein ligand, so it cannot cross the plasma membrane to reach intracellular or nuclear receptors directly.
2. EGF binds the extracellular domain of EGFR; ligand binding promotes receptor dimerization.
3. Dimerization activates the cytosolic tyrosine kinase domains, leading to autophosphorylation of specific tyrosine residues on the receptor.
4. Those phosphorylated residues recruit intracellular signalling molecules, initiating rapid phosphorylation-dependent signalling pathways that produce cellular responses such as proliferation or differentiation.

Why the correct option is correct:
The answer choice that emphasizes promotion of receptor autophosphorylation captures the hallmark mechanism of EGF action: ligand-induced activation of an RTK and autophosphorylation that initiates intracellular signalling. That is the essential, immediate biochemical event following EGF binding.

Why the other choices are incorrect:
- “Gradual effects that last an extended period” better describes steroid hormones that act through nuclear receptors and transcriptional changes; EGF typically initiates faster signalling.
- “Be highly lipid-soluble to access nuclear receptors” is false for peptide growth factors, which are hydrophilic and act at membrane receptors.
- “Initiate rapid signalling that does not require phosphorylation” is incorrect because RTK signalling depends critically on phosphorylation events.

Conclusion: The provided answer—promote autophosphorylation of the extracellular domains of its receptor (intended to indicate promotion of receptor autophosphorylation)—is the correct choice.

A protein such as epidermal growth factor (EGF) is MOST LIKELY to:单项选择题

类似问题

Why are membrane receptors required for insulin signalling?

Which statement explains how the same second-messenger molecule, cAMP, can be involved in different pathways in different cells?

An agonist is a ligand that binds to, and provokes a signal from a receptor via conformational changes in the excited state.

Which of the following is NOT an example of a receptor tyrosine kinase?[Fill in the blank]

Question at position 44 A hormone is an example of which type of cell cycle signal?endogenousexogenous

G protein receptor is a

Which of the following will be affected by a compound that gets rid of ATP?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单