Titin, the largest known protein in the body expressed in three isoforms (N2A, N2BA and N2B), is essential for muscle structure, force generation, conduction and regulation. Since the 1950s, muscle contraction mechanisms have been explained by the sliding filament theory involving thin and thick muscle filaments, while the contribution of cytoskeleton in force generation and conduction was ignored. With the discovery of insoluble protein residues and large molecular weight proteins in muscle fibers, the third myofilament, titin, has been identified and attracted a lot of interests. The development of single molecule mechanics and gene sequencing technology further contributed to the extensive studies on the arrangement, structure, elastic properties and components of titin in sarcomere. Therefore, this paper reviews the structure, isforms classification, elastic function and regulatory factors of titin, to provide better understanding of titin.
Connectin/genetics* ; Muscle Proteins/metabolism* ; Protein Isoforms/genetics* ; Sarcomeres/metabolism* ; Muscle Fibers, Skeletal/metabolism*

Lipoxygenases (linoleate: oxygen oxidoreductase, EC 1.13.11.12; LOXs) are encoded by a multi-gene family in plants. The LOXs are monomeric non-heme, non-sulfur iron dioxygenases, which catalyze the incorporation of molecular oxygen into polyunsaturated fatty acids containing a cis, cis-1,4-pentadiene moiety. The LOX isoforms are distinguished by differences in optimum pH of the reaction, pI, substrate and product specificity, spatial and temporal expression, and subcellular localization. The function of various LOXs in plants has been suggested. Some of the physiological processes in which lipoxygenases have been implicated include wounding, pathogen attack, seed germination, fruit ripening, plant senescence, and synthesis of Abscisic acid (ABA) and Jasmonic acid (JA). During normal vegetative and reproductive growth, lipoxygenases have also been suggested to act as vegetative storage proteins, participate in transference of lipoid, and response to nutrient stress and source/sink relationships. Significant progress in understanding LOX families will be beneficial to the application of the LOX in crop breeding, research on new-type phytoalexin and food industry.
Gene Expression Regulation, Plant ; Lipoxygenase ; genetics ; metabolism ; Multigene Family ; Plants ; enzymology ; Protein Isoforms ; genetics ; metabolism

Humans ; Inhibitor of Apoptosis Proteins ; Microtubule-Associated Proteins ; genetics ; metabolism ; Protein Isoforms ; genetics ; metabolism ; Stomach Neoplasms ; genetics ; metabolism ; Tumor Cells, Cultured

Metallothioneins (MTs) are a group of intracellular proteins of low molecular weight and rich cysteine, encoded by a family of genes containing at least 10 functional isoforms in human. MTs widely exist in the male reproductive system and are involved in many pathophysiological processes such as metal ion homeostasis and detoxification, protection against oxidative damage, cell proliferation and apoptosis, chemoresistance and radiotherapy resistance. This review describes the location and effects of MTs in the male reproductive system.
Gene Expression Profiling ; Genitalia, Male ; metabolism ; physiopathology ; Humans ; Male ; Metallothionein ; genetics ; metabolism ; physiology ; Protein Isoforms ; genetics ; metabolism ; physiology

Survivin variants specific real time quantitative RT-PCR was developed to analyze their expression in 53 paired cancer and para-cancerous tissues, and the expression of the wild-type survivin protein was detected by immunohistochemistry. The results showed that survivin mRNA and protein were expressed in gastric cancer and para-cancerous tissues. The survivin-2B was dominantly expressed in para-cancerous tissues, whereas the survivin-DeltaEx3 was more frequently detected in cancer tissues. The positive rate of survivin-2a was 100% in both cancer and para-cancerous tissues, but its relative transcript expression level was not significantly increased in cancer tissues in comparison with para-cancerous tissues. The correlation analysis revealed that the expression of survivin-2a mRNA was significantly associated with that of total survivin (r (s)=0.4178, P=0.0018), whereas inversely to that of survivin-DeltaEX3 (r (s)=-0.4506, P=0.0007). It was suggested that survivin-2a may act as an antagonist of survivin-DeltaEX3. The balance between antiapoptotic survivin iso-forms and nonantiapoptotic ones may play an important role in tumorigenesis and tumor progression. Promising value is hinted to analyze survivin and its variants in tumor early diagnosis and distinguishing malignant tumors from benign ones.
Microtubule-Associated Proteins/genetics ; Microtubule-Associated Proteins/*metabolism ; Protein Isoforms/genetics ; Protein Isoforms/metabolism ; RNA, Messenger/genetics ; RNA, Messenger/metabolism ; Stomach Neoplasms/*metabolism ; Stomach Neoplasms/pathology ; Tumor Cells, Cultured ; Tumor Markers, Biological/genetics ; Tumor Markers, Biological/*metabolism

OBJECTIVE: In order to supply an effective reference of early injury time estimation and explore the time limit of detection of EDA\EDB mRNA in human skin samples, the expression of alternative splicing segment of fibronectin--EDA\EDB in incised wound of human skin were studied. METHODS: Using in situ hybridization with DIG-labeled anti-sense RNA probe, the expression of FN EDA\EDB domain was detected in human skin incised wound at the early stage of injury (from 30 min to 3 h). RESULTS: The positive expression rates of FN-EDA\EDB immediately after injury and area far away from wound were same as the control group. The expression of FN-EDA\EDB in human skin incised wound showed a gradually increased tendency in early injury time (within 3 h). The positive expression cells were mainly distributed in basement cells of epidermis and the expression of EDA is much higher than EDB. It's difficult to detect EDA\EDB mRNA when the samples were deposited in air for 4 hour. CONCLUSION FN-EDA\EDB may be used as a sensitive mark for the estimation of early injury time. The in-situ hybridization technique is not applicable in the application.
Fibronectins/genetics* ; Forensic Medicine ; Humans ; In Situ Hybridization ; Protein Isoforms/genetics* ; RNA, Messenger/genetics* ; Skin/metabolism* ; Time Factors ; Wound Healing/physiology*

PRAS40, a proline-rich Akt substrate of 40 kD, is 14-3-3 binding protein. To study the interaction between PRAS40 and 14-3-3 isoforms, We constructed the expression vector pEG-PRAS40 (DNA-binding plasmid) and pJG-PRAS40 (transcriptional activity plasmid) in yeast using gateway cloning technology, then the plasmid of pEG-PRAS40/pJG-PRAS40 was co-transformed into yeast EGY48 strain with each pJG-14-3-3 /pEG-14-3-3 isoform plasmid. The co-transformation were tested by nutrition limitation growth analysis, beta-galactosidase color assay was used to study the interaction degree between PRAS40 and 14-3-3 isoforms. We confirmed successfully the construction of pJG-PRAS40 and pEG-PRAS40 with enzyme digestion. four 14-3-3 isoforms were found interacting with PRAS40 using yeast two-hybrid assay, the interaction degree of Epsilon was stronger than beta and zeta, tau was the weakest. Our result will be used to further study the biological function of PRAS40 and 14-3-3 as new drug target.
14-3-3 Proteins ; genetics ; metabolism ; Adaptor Proteins, Signal Transducing ; Humans ; Phosphoproteins ; genetics ; metabolism ; Protein Binding ; Protein Isoforms ; genetics ; metabolism ; Two-Hybrid System Techniques

Inhibin, which is important for normal gonadal function, acts on the pituitary gonadotropins to suppress folliclestimulating hormone (FSH) secretion. The level and cellular localization of the inhibin isotypes, alpha, beta(A) and beta(B), in the testis of mice were examined during postnatal development in order to determine if inhibin expression is related to testicular maturation. Mouse testes were sampled on postnatal days (PNDs) 1, 3, 6, 18, 48 and 120, and analyzed by Western blotting and immunofluorescence. Western blot analysis showed very low levels of inhibin alpha, beta(A) and beta(B) expression in the testes at days 1 to 6 after birth. The levels then increased gradually from PND 18 to 48-120, and there were significant peaks at PND 48. Inhibin alpha, beta(A) and beta(B) were detected in testicular cells during postnatal development using immunohistochemistry. The immunoreactivity of inhibin alpha was rarely observed in testicular cells during PND 1 to 6, or in the cytoplasmic process of Sertoli cells surrounding the germ cells and interstitial cells during PND 18 to 120. Inhibin beta(A) and beta(B) immunoreactivity was rarely observed in the testis from PND 1 to 6. On the other hand, it was observed in some spermatogonial cells, as well as in the interstitial space between PND 48 and PND 120. We conclude that the expression of inhibin isotypes increases progressively in the testis of mice with increasing postnatal age, suggesting that inhibin is associated with a negative feedback signal for FSH in testicular maturation.
Aging/*physiology ; Animals ; Gene Expression Regulation/*physiology ; Inhibin-beta Subunits/genetics/*metabolism ; Inhibins/genetics/*metabolism ; Male ; Mice ; Mice, Inbred ICR ; Protein Isoforms/metabolism ; Protein Transport/*physiology ; Testis/*metabolism

OBJECTIVE: To investigate the expression of myosin heavy chain (MHC) in normal laryngeal muscle and the difference between the adductor and abductor. METHOD: Seven patients with total laryngectomy were enrolled in this study. The adductor muscles were acquired from the lateral cricoarytenoid (LCA) muscle and the abductor muscles were acquired from the posterior cricoarytenoid (PCA) muscle. The expression of myosin heavy chain were detected with fluorescent quantitative reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescence staining respectively. RESULT: (1) MHC-II b was expressed in laryngeal muscles at mRNA levels, and not expressed at the protein level; (2) At both mRNA level and protein level, the expression of MHC-I was higher in the PCA muscles than in the LCA muscles while MHC-II level was higher in the LCA muscles than in the PCA muscles. CONCLUSION (1) MHC-II b protein was not expressed in human laryngeal muscles; (2) Phenotypic differences were significant in laryngeal adductor and abductor muscles based on their different functions. PCA contained larger percentage of MHC-I fibers, while LCA contained more MHC-II fibers.
Aged ; Female ; Humans ; Laryngeal Muscles ; chemistry ; metabolism ; Male ; Middle Aged ; Myosin Heavy Chains ; genetics ; metabolism ; Phenotype ; Protein Isoforms

AIMTo detect the expression of ryanodine receptor (RyR) subtypes in normol rat airway smooth muscle cells(ASMCs) and changes during chronic asthma formation.

METHODSASMCs were cultured with collagen enzyme digestion method. The expression of subtypes of RyR were detected by RT-PCR. Purified PCR product linked with pGEM-T vector to make DNA sequence assay. Chronic asthma model was made with OVA, the changes of RyRs detected by RT-PCR.

RESULTSAll subtypes of RyR were expressed in airway smooth muscle cells of normol rat. The expression of RyR1 increased obviously compared with control group (P < 0.05) on chronic asthma.

CONCLUSIONCo-expression of three subtypes of RyR in ASMCs of normal rat, indicate that there are complicated intercellular Ca2+ regulation mechanism in ASM, moreover RyR1 might play a role during asthma development.

Animals ; Asthma ; metabolism ; Bronchi ; Male ; Myocytes, Smooth Muscle ; metabolism ; Protein Isoforms ; genetics ; metabolism ; RNA, Messenger ; genetics ; Rats ; Rats, Wistar ; Ryanodine Receptor Calcium Release Channel ; genetics ; metabolism