生命科学科研大百科

按照荧光颜色分类，可以更加直观地认识这些常用荧光蛋白的特点。从蓝色、青色、绿色、黄色，到橙红色、远红色，不同波长的荧光蛋白各自承担着不同的科研任务。

Redox homeostasis denotes the maintenance of the balance between oxidants and antioxidants. Although excessive oxidant production causes oxidative damage to cellular biomolecules and results in oxidative distress, lack of adequate oxidant levels impairs crucial signalling processes and results in reductive distress.

The Bcl-2 family consists of a number of evolutionarily conserved proteins containing Bcl-2 homology domains (BH) that regulate apoptosis through control of mitochondrial membrane permeability and release of cytochrome c. Four BH domains have been identified (BH1-4) that mediate protein interactions. The family can be separated into three groups based upon function and sequence homology: pro-survival members include Bcl-2, Bcl-xL, Mcl-1, A1 and Bcl-w; pro-apoptotic proteins include Bax, Bak and Bok; and "BH3 only" proteins Bad, Bik, Bid, Puma, Bim, Bmf, Noxa and Hrk. Interactions between death-promoting and death-suppressing Bcl-2 family members has led to a rheostat model in which the ratio of pro-apoptotic and anti-apoptotic proteins controls cell fate. Thus, pro-survival members exert their behavior by binding to and antagonizing death-promoting members. In general, the "BH3-only members" can bind to and antagonize the pro-survival proteins leading to increased apoptosis. While some redundancy of this system likely exists, tissue specificity, transcriptional and post-translational regulation of many of these family members can account for distinct physiological roles.

Apoptosis is a regulated physiological process leading to cell death. Caspases, a family of cysteine acid proteases, are central regulators of apoptosis. Initiator caspases (including 2, 8, 9, 10 and 12) are closely coupled to proapoptotic signals, which include the FasL, TNF-α, and DNA damage. Once activated, these caspases cleave and activate downstream effector caspases (including 3, 6 and 7), which in turn cleave cytoskeletal and nuclear proteins like PARP, α-fodrin, DFF and lamin A, and induce apoptosis.

Pro-Apoptosis Bcl-2 Family Antibody The Bcl-2 family consists of a number of evolutionarily conserved proteins containing Bcl-2 homology domains (BH) that regulate apoptosis through control of mitochondrial membrane permeability and release of cytochrome c. Four BH domains have been identified (BH1-4) that mediate protein interactions. The family can be separated into three groups based upon function and sequence homology: pro-survival members include Bcl-2, Bcl-xL, Mcl-1, A1 and Bcl-w; pro-apoptotic proteins include Bax, Bak and Bok; and "BH3 only" proteins Bad, Bik, Bid, Puma, Bim, Bmf, Noxa and Hrk. Interactions between death-promoting and death-suppressing Bcl-2 family members has led to a rheostat model in which the ratio of pro-apoptotic and anti-apoptotic proteins controls cell fate (4). Thus, pro-survival members exert their behavior by binding to and antagonizing death-promoting members. In general, the "BH3-only members" can bind to and antagonize the pro-survival proteins leading to increased apoptosis. While some redundancy of this system likely exists, tissue specificity, transcriptional and post-translational regulation of many of these family members can account for distinct physiological roles.

The synapse is the unit of information transfer in the brain between neurons. Synaptic transfer is initiated by action potential-initiated synaptic vesicles fusion at the presynaptic terminal to release neurotransmitters. The basic molecular machinery that drives all membrane fusion events in all cells include N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins that form a trans-ternary complex between to-be-fused membranes. The zippering up of SNARE proteins provides the energy required for membrane fusion. At the synapse, the SNARE proteins include 25 kDa synaptosome-associated protein (SNAP25), syntaxin 1A (STX1A), and vesicle-associated membrane protein 2 (VAMP2, also called synaptobrevin). Neurotransmitter release, however, is a highly regulated process that occurs in response to action potential-initiated Ca2+-influx. Regulation of synaptic vesicle fusion is mediated by SNARE-binding proteins like complexin and the Ca2+-associated vesicle protein, synaptotagmin-1, that cooperatively function to initiate Ca2+-induced synaptic vesicle fusion. The synaptic vesicle cycle represents a cycle of events that prime the synaptic vesicle before fusion and retrieve fused membrane after full fusion. Synaptic vesicle-associated proteins like synaptophysin and synapsin-1, as well as target membrane proteins like Munc18-1, play a complex role in priming synaptic vesicles to be fusion competent.

AMPK is a heterotrimeric complex composed of a catalytic α subunit and regulatory β and γ subunits, each of which is encoded by two or three distinct genes (α1, 2; β1, 2; γ1, 2, 3). The kinase is activated by an elevated AMP/ATP ratio due to cellular and environmental stress, such as heat shock, hypoxia, and ischemia. The tumor suppressor LKB1 phosphorylates AMPKα at Thr172 in the activation loop, and this phosphorylation is required for AMPK activation. Accumulating evidence indicates that AMPK not only regulates the metabolism of fatty acids and glycogen, but also modulates protein synthesis and cell growth through EF2 and TSC2/mTOR pathways, as well as blood flow via eNOS/nNOS.

The polycomb group (PcG) proteins contribute to the maintenance of cell identity, stem cell self-renewal, cell-cycle regulation, and oncogenesis by maintaining the silenced state of genes that promote cell lineage specification, cell death, and cell-cycle arrest. PcG proteins exist in two complexes that cooperate to maintain long-term gene silencing through epigenetic chromatin modifications. The first complex, Eed-Ezh2, is recruited to genes by DNA-binding transcription factors and methylates histone H3 on Lys27. This histone methyltransferase activity requires the Ezh2, Eed, and Suz12 subunits of the complex. Methylation of Lys27 facilitates the recruitment of the second complex, PRC1, which ubiquitinates histone H2A on Lys119. PRC1 is composed of Bmi1 and RING1A (also RING1 or RNF1), both of which act to enhance the E3 ubiquitin ligase activity of an additional catalytic subunit RING1B (also RING2 or RNF2). PcG proteins play an important role in the regulation of cell proliferation and senescence through repression of the p16 INK4A and p19 ARF genes and are required for maintenance of adult hematopoietic and neural stem cells, as well as embryonic stem cells.

Phosphoinositide-specific phospholipase C (PLC) plays a significant role in transmembrane signaling. In response to extracellular stimuli, such as hormones, growth factors, and neurotransmitters, PLC hydrolyzes phosphatidylinositol 4,5-bisphosphate (PIP2) to generate two secondary messengers: inositol 1,4,5-triphosphate (IP3) and diacylglycerol (DAG). At least four families of PLCs have been identified: PLCβ, PLCγ, PLCδ, and PLCε. Phosphorylation is one of the key mechanisms that regulate the activity of PLC. PLCγ is activated by both receptor and non-receptor tyrosine kinases. PLCγ forms a complex with EGF and PDGF receptors, which leads to the phosphorylation of PLCγ at Tyr771, 783, and 1248. Phosphorylation by Syk at Tyr783 activates the enzymatic activity of PLCγ1. PLCγ2 is engaged in antigen-dependent signaling in B cells and collagen-dependent signaling in platelets. Phosphorylation by Btk or Lck at Tyr753, 759, 1197, and 1217 is correlated with PLCγ2 activity.

The Na,K-ATPase is an integral membrane heterodimer belonging to the P-type ATPase family. Phosphorylation of Na,K-ATPase at Tyr10 has been implicated in the regulation of enzyme activity in response to hormones and neurotransmitters. Cadherins are a superfamily of transmembrane glycoproteins that contain cadherin repeats of approximately 100 residues in their extracellular domain. Cadherins mediate calcium-dependent cell-cell adhesion and play critical roles in normal tissue development. The classic cadherin subfamily includes N-, P-, R-, B-, and E-cadherins, as well as about ten other members that are found in adherens junctions, a cellular structure near the apical surface of polarized epithelial cells. 4F2hc is a transmembrane protein that belongs to the solute carrier family. 4F2hc forms heterodimeric complexes with various amino acid transporters, such as LAT1 and LAT2, and regulates uptake of amino acids. The 21-24 kDa integral proteins, caveolins, are the principal structural components of the cholesterol/sphingolipid-enriched plasma membrane microdomain caveolae. Three members of the caveolin family (caveolin-1, -2, and -3) have been identified with different tissue distributions. Ectonucleotide pyrophosphatase-phosphodiesterase 1 (ENPP1) is a single-pass, type II transmembrane protein primarily involved in ATP hydrolysis at the plasma membrane. ENPP1 plays important roles in bone mineralization and soft tissue calcification.