Palindromes in Proteins

Palindromes in DNA consist of nucleotides sequences that read the same from the 5′-end to the 3′-end, and its double helix is related by twofold axis. They occur in genomes of all organisms and have various functions. For example, restriction enzymes often recognize palindromic sequences of DNA. Palindromes in telomeres are crucial for initiation of replication. One can ask the questions, Do palindromes occur in protein, and if so, what function they play? We have searched the protein SWISSPROT database for palindromic sequences. A great number (26%) of different protein palindromes were found. One example of such protein is systemin, an 18-amino-acid-long peptide. It contains palindrome in its β-sheet domain that interacts with palindromic fragment of DNA. The other palindrome containing protein is cellular human tumor suppressor p53. Oligonucleotide LTIITL has been observed in the crystal structure and is located close to a DNA recognizing domain. As the number of possible palindromic sequences of a given length is far much greater for proteins (20^N) than for nucleic acids (4^N), the study on their role seems to be an exciting challenge. Our results have clearly showed that palindromes are frequently occurring motives in proteins. Moreover, even very few examples that we have examined so far indicate the importance of further studies on protein palindromes.     

Comparison of Canavanyl-Envelope Proteins to Normal Envelope Proteins

Electrophoretic analysis showed arginine- and canavanine-containing envelope proteins to be qualitatively the same. Quantitative differences may be due to rapid degradation of some canavanine-containing envelope proteins.     

Proteins

Proteins continue to surprise and amaze us in the myriad of ways in which they achieve biological function. The Proteins section in this issue of Current Opinion in Structural Biology highlights several proteins in which large conformational changes and evolutionary divergence in structure and function, play essential roles in their adaptation to a variety of biological functions. In addition, fundamental advances have been made in research, spurred on by industrial interest in the use of proteins as drug targets or as catalysts. All of the reviews in this section document the fact that multiple crystal structures of a protein in different functional states, and of different members of protein families, are necessary for the composition of a complete structural picture.     

Virus-Induced Proteins in Pseudorabies-Infected Cells I. Acid-Extractable Proteins of the Nucleus

Three basic proteins have been identified in chromatin preparations from pseudorabies virus-infected cells. They appear to be virus specified and are similar in size and charge to host histones; one difference however is that they contain tryptophan. All are produced by 3 h postinfection, and two (IP II and III) seem to be arginine rich. Three similar proteins are also found in herpes simplex MP 17-infected cells, and two of these co-electrophorese with two of the pseudorabies proteins. Partially purified preparations of pseudorabies virus contain low amounts of all three proteins.     

Staining Proteins in Gels

Following separation by electrophoretic methods, proteins in a gel can be detected by several staining methods. This unit describes protocols for detecting proteins by four popular methods. Coomassie blue staining is an easy and rapid method. Silver staining, while more time consuming, is considerably more sensitive and can thus be used to detect smaller amounts of protein. Fluorescent staining is a popular alternative to traditional staining procedures, mainly because it is more sensitive than Coomassie staining, and is often as sensitive as silver staining. Staining of proteins with SYPRO Orange and SYPRO Ruby are also demonstrated here.Download video file.^{(121M, mp4)}     

Isoprenylated Proteins in Myelin

Abstract: Incubation of rat brainstem slices with [³H]- mevalonate ([³H]MVA) in the presence of lovastatin resulted in the incorporation of label into three groups of myelin-associated proteins with molecular masses of 47, 21–27, and 8 kDa, as revealed on sodium dodecyl sulfate- polyacrylamide rod gel electrophoresis. Although the gel patterns of [³H]MVA-derived prenylated proteins were similar, the relative level of ³H incorporated into each protein species differed between myelin and the brainstem homogenate. Immunoprecipitation studies identified the 47-kDa prenylated protein as a 2′-3′-cyclic nucleotide phospho- diesterase, whereas the 8-kDa protein proved to be the γ subunit of membrane-associated guanine nucleotide regulatory protein. The ³H-labeled 21–27-kDa group in myelin corresponds to the molecular mass of the extensive Ras- like family of monomeric GTP-binding proteins known to be prenylated in other tissues. Increase in lovastatin concentration resulted in reduced levels of [³H]MVA-labeled species in myelin and concomitantly increased levels in the cytosol. A cold MVA chase restored to normality the appearance of [³H]MVA-labeled proteins in myelin. Furthermore, a high lovastatin concentration in the brainstem slice incubation mixture altered the appearance of newly synthesized nonprenylated myelin proteins, including proteolipid protein and the 17-kDa subspecies of myelin basic protein. Because other myelin proteins were unaffected by the high lovastatin concentration, restricting the availability of MVA in myelin-forming cells may selectively alter processes required for myelinogenesis. Although the molecular basis for the” different MVA requirements in myelin- forming cells remains undefined, it may involve an alteration in the biological activity of certain proteins that require prenylation to be functionally active, and that are responsible for promoting insertion of specific proteins into the myelin membrane.     

植物的MYB蛋白

植物MYB蛋白是一类DNA结合蛋白。文章对其结构特征和生理功能 ,其与DNA的相互作用及DNA结合区域的进化、MYB基因功能丰余性方面作了简要介绍。     

植物的冷调节蛋白

冷害是世界范围内普遍存在的问题。冷驯化是通过低温诱导植物形成抗冷力的过程。冷调节蛋白是植物在冷驯化下产生的特异性蛋白质 ,与植物的抗冷力密切相关。随着分子生物技术的发展 ,成为近年来抗冷生理研究的热点之一。本文介绍了植物冷调节蛋白的分布、结构、性质、功能及诱导调控等方面的最新研究进展 ,并展望了将来的研究方向。     

植物的干旱诱导蛋白

就干旱诱导蛋白的类型,产生,特性,定位,生理 功能,基因及表达调控方面作了简要的综述。     

Proteins in organic solvents

Catalysis in organic solvents and the mapping of protein surfaces using multiple solvent crystal structures are two rapidly developing areas of research. Recent advances include the study of protein folding and stability in different solvents, and the demonstration that it is possible to qualitatively rank the affinities of protein binding sites for a given organic solvent using the multiple solvent crystal structures method.