概括
细菌蛋白质降解涉及ATP刺激的膜蛋白酶,这些蛋白质分解为. 然后可溶性酶将这些完全化成氨基酸.
科学领域:
- 微生物学 微生物学
- 生物化学 生物化学
- 细胞生物学 细胞生物学
背景情况:
- 蛋白质降解在细菌中至关重要,但其机制和酶仍然不清楚.
- 产生ATP对于细菌和动物细胞中的蛋白质分解至关重要.
- 以前的研究表明,ATP刺激细胞提取物中的蛋白质分解.
研究的目的:
- 研究负责细菌蛋白质降解的途径和酶.
- 为了确定ATP在细胞内蛋白质溶解中的作用.
- 描述涉及降解细胞蛋白质的特定蛋白酶.
主要方法:
- 在各种条件下 (生长,饥饿) 研究了大肠杆菌中的蛋白质降解.
- 利用细胞提取物来证明ATP刺激的蛋白解.
- 对蛋白酶活性进行研究的膜片段.
- 分析了蛋白质分解的产物 (和氨基酸).
主要成果:
- 鉴定了一种位于细菌膜碎片中的ATP刺激蛋白酶.
- 这种蛋白酶将细胞蛋白降解为大型 (MW 71,500).
- 可溶性,不依赖ATP的酶迅速将这些酸化为氨基酸.
结论:
- 细菌蛋白质降解涉及两个步骤的过程:膜结合的ATP刺激蛋白解,然后是可溶性ATP独立的水解.
- 这一途径有助于正常和异常蛋白质的降解.
- 这些发现阐明了细菌蛋白质解和酶功能的关键方面.
相关概念视频
Translocation of Proteins into the Mitochondria
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Insertion of Single-pass Transmembrane Proteins in the RER
Integral membrane proteins are proteins adhered to the lipid bilayer of a cell organelle or membrane. They can be of two types: transmembrane integral proteins that span the lipid bilayer and monotopic proteins that are attached to either side of the membrane but do not pass through it.
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Tail-anchoring of Proteins in the ER Membrane
Tail-anchored, or TA, proteins are estimated to make up to 3-5% of membrane proteins found in the eukaryotic cell. Such proteins have a single transmembrane domain located approximately 30 amino acid residues upstream from the C-terminal end. As a result, the signal recognition particle (SRP) cannot guide a TA protein to the ER membrane for cotranslational insertion. Hence, they are integrated into the ER membrane post-translationally using their C-terminal end as the anchor. TA proteins...
Post-translational Translocation of Proteins to the RER
A sizable fraction of proteins destined for ER are first synthesized in the cell cytosol and then transported across the ER membrane–a process called post-translational translocation. Similar to cotranslationally translocated proteins, these proteins also use the Sec translocon complex to enter the ER lumen.
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
Protein Translocation Machinery on the ER Membrane
The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into the ER membrane.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
The Proteasome Structure
The ubiquitin-proteasome pathway is a well-known mechanism utilized by eukaryotic cells to remove cytoplasmic proteins that are misfolded, damaged, or no longer needed. In this pathway, the protein that needs to be eliminated undergoes a process called ubiquitination, where a chain of ubiquitin molecules is attached to the 48th lysine residue of the target protein. This ubiquitin modification helps the proteasome distinguish between a target protein and a healthy protein.
The proteasome is an...
The proteasome is an...


