Giant Cell Myocarditis after First Dose of BNT162b2 - a Case Report

Herein we report the case of a young man, admitted to the Department of Cardiology and Angiology at Hannover Medical School with shortness of breath and elevated troponin. Few weeks earlier the patient received the first dose of BioNTech's mRNA vaccine (Comirnaty, BNT162b2). After diagnostic work‐up revealed giant cell myocarditis, the patient received immunosuppressive therapy. In the present context of myocarditis after mRNA vaccination we discuss this rare aetiology and the patient's treatment strategy in the light of current recommendations.

microRNA-206 correlates with left ventricular function after transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) is the method of choice in patients with high risk or contraindications for conventional aortic valve replacement. However, it is not well understood which parameters predict the overall cardiac function postprocedurally. miRNAs are small noncoding RNA molecules that repress gene expression by different mechanisms and can also be detected in the blood. Recent studies have shown that miRNAs detected in the blood may serve as sensitive and specific biomarkers in various diseases; therefore, we examined the levels of different microRNAs in the serum of patients undergoing TAVI. We thereby intended to find potential predictors for cardiac function after TAVI. Serum from patients with aortic valve disease was obtained at five different points: before the TAVI procedure, at days 1 and 3 after the TAVI procedure, and the day of dischargement and after a period of 3 mo. We next performed quantitative real-time PCRs to examine the samples for changes in the level of miRNAs previously described as cardiac enriched. Our results show that the level of miR-206 in the serum of patients after TAVI correlated negatively with the left ventricular ejection fraction of individual patients. We found left ventricular function to be better in patients with lower levels of miR-206 after implantation of the new valve. A decrease in the serum level of miR-206 may be linked to changes in cardiac function of patients after TAVI. Further studies are necessary to test the miRNA for its potential value as a prognostic marker. NEW & NOTEWORTHY This study is the first to investigate novel miRNA-based biomarkers within the context of transcatheter aortic valve implantation. miRNA-206 proved to correlate inversely with the postprocedural left ventricular ejection fraction of patients.

Catheter fragmentation and local lysis in two lung transplant patients with pulmonary embolism

In conjunction with the rising number of lung transplant operations in the past decade, an increased predisposition to venous thrombosis (VT), particularly within the first year posttransplantation has been observed. Previous studies have revealed that between 8.6% and 12% of patients develop VT, which can ultimately result in pulmonary emboli (PE).Transplanted lungs pose a much greater infarction risk due to their lack of collateral vascularisation, relying entirely on the vasa publica--the pulmonary artery--in the absence of vasa privata. Such losses in viable lung parenchyma are always serious, but carry still greater risks for single-lung transplant recipients, an early diagnosis and treatment remain critical. Here we report on two cases of PE after lung transplantation, both of whom were managed with catheter fragmentation and local thrombolysis. In our opinion, this approach represents a viable treatment for symptomatic PE in lung transplant recipients. The benefits and risks of the alternative treatment options in these special cases will be reviewed and the definitive therapy was described. In the patients treated, catheter fragmentation with localized thrombolysis resulted in short term improvements in graft function, but could not prevent later lung infarction in one case.

[Pathophysiology of heart failure]

Chronic heart failure is a clinical syndrome and the final common pathway of different cardiac diseases. Heart failure is accompanied by activation of the renin-angiotensin-aldosterone-system and the adrenergic nervous system. In addition, recent data emphasize important roles of maladaptive intracellular signaling pathways, decreased capillary density, altered calcium handling, metabolic changes, genetic polymorphisms, and programmed cell death in the failing heart. In this context, traditional pathophysiological concepts, e. g. concerning the role of cardiac hypertrophy, had to be given up. Thus, an increasingly complex scenario emerges with interdependent changes on the biochemical, molecular, metabolic, and cellular level. Novel therapeutic strategies may soon be based on these new pathophysiological concepts.

Restriction in the repertoire of the immunoglobulin light chain subgroup in pathological cold agglutinins with anti-Pr specificity

BACKGROUND AND OBJECTIVES

In cold agglutinin disease, monoclonal red blood cell autoantibodies, termed cold agglutinins, induce haemolysis in patients exposed to the cold. Commonly, these autoantibodies are directed against the developmentally regulated I/i blood groups. A second blood group system, the Pr system (located on glycophorins), is involved less frequently. Anti-Pr cold agglutinins recognize either alpha 2,3- or alpha 2,6-linked N-acetylneuraminic acid as the immunodominant group. Cold agglutinins of anti-I/i specificity show a remarkable restriction in their genomic repertoire of the immunoglobulin heavy and light-chain immunoglobulin-variable domain (i.e. exclusive use of VH4-34 in heavy chains). For anti-Pr cold agglutinins, preliminary data on the repertoire of the light-chain variable domain indicate a preference for the subgroup Vkappa IV. To elucidate restrictions in the light-chain variable-domain subgroup repertoire of anti-Pr cold agglutinins systematically, and to discuss these results in the context of their anti-Pr(1-3) subclassification and immunodominant sialic acid, light chains in 13 anti-Pr cold agglutinins were investigated.

MATERIALS AND METHODS

The anti-Pr light chains were isolated using temperature-dependent absorption/elution techniques. Subsequently, they were subjected to N-terminal Edman degradation, and the light chain Vkappa subgroup was affiliated using the Kabat database.

RESULTS

Five of 13 (38%) light chains belonged to Vkappa IV, five of 13 (38%) to Vkappa I and three of 13 (23%) to Vkappa III. Anti-Pr with Vkappa IV subgroup light chains exclusively recognized alpha 2,3-linked N-acetylneuraminic acid.

CONCLUSIONS

Including data from the literature, the repertoire of the light-chain variable domain in pathological anti-Pr cold agglutinins exhibits a clear bias towards the use of the single germline gene-derived subgroup, Vkappa IV (eight of 17 or 47%). The association of Vkappa IV subgroup light chain-containing anti-Pr cold agglutinins with binding to alpha 2,3-, but not alpha 2,6-linked N-acetyneuraminic acid raises speculations about a possible role of subgroup-derived determinants in anti-Pr binding.

EMG remains fractionated in Parkinson's disease, despite practice-related improvements in performance

OBJECTIVE

We studied the ability of patients with Parkinson's disease to improve their performance in a motor task requiring both speed and accuracy in the execution of elbow flexion movements. Our goal was to investigate the changes in electromyographic activity associated with the changes in movement performance.

METHODS

Eleven patients on anti-Parkinsonian medication were tested. The patients were selected for being bradykinetic, having little or no resting tremor or dyskinesias, and being in stages II or III of the Hoehn and Yahr rating scale.

RESULTS

The untrained patients displayed multiple bursts of agonist activity, characteristic of Parkinsonian EMG recordings. All patients improved their performance by increasing peak velocity while maintaining movement accuracy within strict boundaries. With practice, the patients' performance changed in a manner similar to that which has been previously observed for performance curves in neurologically normal subjects. As movement duration decreased (i.e. peak velocity increased), we observed a slight decrease in the number of agonist bursts and an increase in the average burst duration. However, the patients continued to generate a fractionated, multi-burst agonist pattern.

CONCLUSIONS

We conclude that Parkinsonian patients benefit from practice by improving their performance but remain fundamentally impaired in the generation of muscle activation patterns. This study has shown that the generation of fractionated, multiple short bursts of EMG activity that is characteristic of movements made by Parkinsonian patients is not normalized by practice.

C1-esterase-inhibitor treatment at early reperfusion of hemorrhagic shock reduces mesentry leukocyte adhesion and rolling

OBJECTIVE

Complement activation probably plays a pathogenic role in multiple organ failure in shock. This study evaluates the effects of C1-esterase-inhibitor treatment on leukocyte-endothelial interaction in the mesenteric microcirculation in hemorrhagic shock.

METHODS

Rats underwent median laparotomy and exteriorization of an ileal loop for intravital microscopy of the mesenteric microcirculation. Volume controlled hemorrhagic shock was provoked by arterial blood withdrawal (2.5 mL/100 g body wt. for 60 minutes) followed by a 4-hour reperfusion period. C1-INH (100 IU/kg body wt. i.v.) or 0.9% NaCl i.v. were administered as a bolus at the beginning of reperfusion. Reperfusion time mimicked a "pre-hospital" phase of 30 minutes followed by a quasi "in-hospital" phase of 3.5 hours. The "in-hospital" phase was initiated by substitution of blood followed by fluid resuscitation with normal saline.

RESULTS

Application of C1-INH markedly reduced rolling and adherent leukocytes to numbers approaching baseline values. Vmax and shear rate of the mesenteric microcirculation improved in both groups after reperfusion with a trend to higher values in the C1-INH group (n.s. p = 0.08).

CONCLUSION

C1-INH applied in a bolus dose of 100 IU/kg body wt. i.v. abrogated enhanced leukocyte adhesion and rolling in the mesenteric microcirculation after hemorrhagic shock. Single bolus treatment with a complement inhibitor may provide clinical benefit when applied at an early stage of reperfusion during hemorrhagic shock.

The exosome of Trypanosoma brucei

The yeast exosome is a complex of at least 10 essential 3'-5' riboexonucleases which is involved in 3'-processing of many RNA species. An exosome-like complex has been found or predicted to exist in other eukaryotes but not in Escherichia coli. The unicellular parasite Trypanosoma brucei diverged very early in eukaryotic evolution. We show here that T.brucei contains at least eight exosome subunit homologs, but only a subset of these associate in a complex. Accordingly, the T.brucei exosome is smaller than that of yeast. Both free and complex-associated homologs are essential for cell viability and are involved in 5.8S rRNA maturation. We suggest that the exosome was present in primitive eukaryotes, and became increasingly complex during subsequent evolution.

Plasma protein loss during surgery: beneficial effects of albumin substitution

Plasma protein loss during abdominal surgery is a known phenomenon, but its possible pathophysiological relevance has remained unknown. The present study evaluates the effects of albumin substitution on systemic and local hemodynamics and cellular interactions in the mesenteric microcirculation. Rats underwent median laparotomy and exteriorization of an ileal loop for intravital microscopy of the mesenteric microcirculation. Plasma protein concentrations, systemic and local hemodynamics were recorded during the follow up period, with or without albumin substitution. Depending on the time course of plasma protein loss in control experiments, 80% of the calculated protein loss was infused during the first 2 h of surgery, and the other 20% over the following 5 h of intravital microscopy. The control group received a continuous infusion of normal saline. Plasma protein loss was mainly due to loss of albumin. A significant increase in adherent and rolling leukocytes was observed during the course of mesenteric exteriorization, which was almost entirely reversed by albumin replacement. Albumin substitution led to stabilisation of mean arterial pressure and abdominal blood flow and also attenuated reductions in arterial base excess. Albumin infusions to replace plasma protein loss may be a simple and effective measure to attenuate microcirculatory disturbances and may be of benefit in patients undergoing abdominal surgery.

Intracellular location and nuclear targeting of the Spi-1, Spi-2 and Spi-3 gene-derived serine protease inhibitors in non-secretory cells

Proteases and their inhibitors are indispensable for the regulated activation and/or degradation of structural and functional proteins involved in basic cellular processes, e.g. in cell cycle control, cell growth, differentiation and apoptosis. In this context the serine protease inhibitors derived from the murine Spi-1, Spi-2 and Spi-3 genes, and their human homologs, deserve reconsideration. Microsequencing data indicate that a fraction of the three serpins has the capability to constitute a well characterized proteinase K, high salt and SDS-stable complex which coisolates with DNA under salting out conditions from various cell and tissue types. This tight association with DNA isolated under conditions designed to deproteinize DNA efficiently points to an in situ preformed chromatin complex. Accordingly, in addition to their well known functions as 'serum protease inhibitors' the Spi-1 and Spi-2 gene-derived proteins appear to have intracellular functions as well. The involvement of the three serpins in chromatin complexes requires their nuclear translocation. Application of (enhanced) green fluorescent protein technology and optical section microscopy reveals that truncation of the N-terminal signal sequences of the Spi-1 and Spi-2 gene-encoded proteins is a prerequisite for their nuclear translocation while non-truncated fusion proteins are enriched at the nuclear indentation which is the site of the Golgi apparatus and the centrosome. The identification of new species of intracellular serpins is of potential interest with respect to accumulating evidence for serine protease inhibitor-dependent inhibition or prevention of apoptosis.

First isolation of human UDP-D-xylose: proteoglycan core protein beta-D-xylosyltransferase secreted from cultured JAR choriocarcinoma cells

Human UDP-d-xylose:proteoglycan core protein beta-d-xylosyltransferase (EC, XT) initiates the biosynthesis of glycosaminoglycan lateral chains in proteoglycans by transfer of xylose from UDP-xylose to specific serine residues of the core protein. In this study, we report the first isolation of the XT and present the first partial amino acid sequence of this enzyme. We purified XT 4,700-fold with 1% yield from serum-free JAR choriocarcinoma cell culture supernatant. The isolation procedure included a combination of ammonium sulfate precipitation, heparin affinity chromatography, ion exchange chromatography, and protamine affinity chromatography. Among other proteins an unknown protein was detected by matrix-assisted laser desorption ionization mass spectrometry-time of flight analysis in the purified sample. The molecular mass of this protein was determined as 120 kDa by SDS-polyacrylamide gel electrophoresis. The isolated protein was enzymatically cleaved by trypsin and endoproteinase Lys-C. Eleven peptide fragments were sequenced by Edman degradation. Searches with the amino acid sequences in protein and EST data bases showed no homology to known sequences. XT was enriched by immunoaffinity chromatography with an immobilized antibody against a synthetic peptide deduced from the sequenced peptide fragments and was specifically eluted with the antigen. In addition, XT was purified alternatively with an aprotinin affinity chromatography and was detected by Western blot analysis in the enzyme-containing fraction.

The AN2 protein is a novel marker for the Schwann cell lineage expressed by immature and nonmyelinating Schwann cells

The expression of the 330 kDa AN2 glycoprotein was studied in the rodent peripheral nervous system. AN2 is expressed by immature Schwann cells in vitro and in vivo and downregulated as the cells upregulate myelin genes. A subpopulation of nonmyelinating Schwann cells in the adult sciatic nerve retains expression of AN2. In rat sciatic nerve crushes, where Schwann cell numbers increase after initial axonal loss and markers of immature Schwann cells show an upregulation, no increased expression of AN2 was observed. In contrast, AN2 expression was upregulated in nerves from peripheral myelin protein-22-transgenic rats, where immature Schwann cells expand without axonal loss. Furthermore, coculture with neurons upregulated AN2 expression on Schwann cells in vitro. Polyclonal antibodies against AN2 inhibited the migration of an immortalized Schwann cell clone in an in vitro migration assay, and the purified AN2 protein was shown to be neither inhibitory nor permissive for outgrowing dorsal root ganglion neurites. AN2 is thus a novel marker for the Schwann cell lineage. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of purified AN2 from early postnatal mouse brain demonstrated that AN2 is the murine homolog of the rat NG2 proteoglycan.

Time course and temporal order of changes in movement kinematics during motor learning: effect of joint and instruction

Learning a motor task is associated with specific changes in movement kinematics. Recently, it has been shown that changes in different kinematic parameters occurred with different time courses for subjects who practiced simple, single-joint elbow movements. For example, movement time was seen to decrease and level off in a shorter time than peak velocity, which increased and plateaued later. What is not known, however, is whether the time course and temporal order of these learning-related changes seen at the elbow are similar for movements learned at other joints and with different instructions. In this study, neurologically normal subjects practiced 50 degrees -flexion movements made at the wrist, with the instruction to be both "fast and accurate" (same instruction used in the earlier elbow study). A different group of subjects practiced wrist movements of the same amplitude, but with instructions to make movements that were "always accurate;" only as movement skill developed could subjects increase their speed (but without ever sacrificing accuracy). We measured time-related parameters (duration of acceleration, duration of deceleration, and total movement duration) and magnitude-related parameters (peak velocity, peak acceleration, and peak deceleration). We found that the time course of changes in kinematic parameters for subjects instructed to be "fast and accurate" was similar to that reported at the elbow. When the instruction was changed to be "always accurate," the time for changes in kinematic parameters to level off was found to be longer. However, regardless of instruction, time-related parameters plateaued before magnitude-related parameters. Thus, our results indicate that motor learning mechanisms may operate in a similar way at different joints.

Plastic foil technique attenuates inflammation in mesenteric intravital microscopy

BACKGROUND

Interpretation of intravital microscopic observations is complicated by the "inflammatory"-type response to the trauma inflicted on the tissue by the surgical preparation. The present study evaluates different experimental conditions for prolonged observations of the mesenteric microcirculation in the rat.

METHODS

The mesentery was exteriorized through a median laparotomy and subjected to an organ bath or a modified plastic foil technique. Hemodynamic, metabolic, respiratory, and microcirculatory data were analyzed.

RESULTS

In contrast to the plastic foil technique, which yielded stable baseline values over a 5-h observation period, venular velocity and wall shear rates decreased significantly in the organ bath technique, and leukocyte adhesion to the endothelium was significantly increased. Likewise, abdominal blood flow decreased significantly by 35% and base excess declined (-10.0+/-0.4 mmol/L) in the organ bath, with reduced pco(2) (26.4+/-2.5 mm Hg vs. 33.7+/-1.1 mm Hg in plastic foil technique) due to respiratory pH compensation.

CONCLUSIONS

The plastic foil technique was found clearly superior to the organ bath technique for maintenance of stable baseline metabolic, hemodynamic, and microcirculatory conditions in mesenteric intravital microscopy.

Time course and temporal order of changes in movement kinematics during learning of fast and accurate elbow flexions

Learning of a motor task, such as making accurate goal-directed movements, is associated with a number of changes in limb kinematics and in the EMG activity that produces the movement. Some of these changes include increases in movement velocity, improvements in end-point accuracy, and the development of a biphasic/triphasic EMG pattern for fast movements. One question that has remained unanswered is whether the time course of the learning-related changes in movement parameters is similar for all parameters. The present paper focuses on this question and presents evidence that different parameters evolve with a specific temporal order. Neurologically normal subjects were trained to make horizontal, planar movements of the elbow that were both fast and accurate. The performance of the subjects was monitored over the course of 400 movements made during experiments lasting approximately 1.5 h. We measured time-related parameters (duration of acceleration, duration of deceleration, and movement duration) and amplitude-related parameters (peak acceleration, peak deceleration, peak velocity), as well as movement distance. In addition, each subject's reaction time and EMG activity was monitored. We found that reaction time was the parameter that changed the fastest and that reached a steady baseline earliest. Time-related parameters decreased at a somewhat slower rate and plateaued next. Amplitude-related parameters were slowest in reaching steady-state values. In subjects making the fastest movements, a triphasic EMG patterns was observed to develop. Our findings reveal that movement parameters change with different time courses during the process of motor learning. The results are discussed in terms of the neural substrates that may be responsible for the differences in this aspect of motor learning and skill acquisition.

One step isolation of bovine asialoglycoprotein receptor and its characterization by sequence analysis and MALDI mass spectrometry

The asialoglycoprotein receptor (ASGP-R), which is responsible for the uptake of partially deglycosylated serum glycoproteins was isolated from bovine liver. The receptor was purified in one step from solubilized plasma membranes by affinity chromatography on 6-(beta-D-lactosyl)-n-hexylamine coupled to N-hydroxysuccinimide activated Sepharose with a coupling degree of 7.6 micromol/ml gel. The preparation yielded two distinct polypeptides with apparent molecular weights of 48 and 43 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A polyclonal antibody raised against the human ASGP-R recognized the bovine 43 kDa protein in Western blot analysis. The 48 and 43 kDa polypeptides were digested by trypsin and the digests were subsequently analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Sequence analysis of four tryptic fragments, two each of the 48 kDa and of the 43 kDa polypeptides revealed that these were highly homologous to ASGP-R subunits from man, mouse and rat.

A multifunctional protein: involvement of the alpha-1 serum protease inhibitor in SDS and high salt-stable DNA-protein complexes

Occasionally new and intriguing roles arise for proteins with well established functions. The alpha-1 serum protease inhibitor (alpha-1 PI) represents another example. Sequence identities exist in the alpha-1 PI and in a nuclear 52-kDa glycoprotein which is involved in resistant DNA-polypeptide complexes. The results of Western blots support the identity of the two proteins and immunocytochemical studies indicate the nuclear location of the alpha-1 PI. Consistently, e.g. Ehrlich ascites tumor cells express the alpha-1 PI, and the fusion protein between the alpha-1 PI and the green fluorescent protein from Aequorea victoria shows intracellular accumulation and partly nuclear location.

Optimized method for determination of gabapentin in serum by high-performance liquid chromatography

The anticonvulsant drug gabapentin and its heptaneacetic acid analog-used here as an internal standard--are isolated from serum (pH 9) with an octyldecyl (C-18) solid-phase sorbent column. To enhance analytical detection, trinitrobenzene derivatives of these extracted compounds are prepared quickly within 10 min. To further improve chromatographic selectivity, the derivatives are concentrated on a thin C-18 solid-phase membrane and interferences are washed away. The retained purified derivatives are eluted from the membrane with a small volume of solvent and the eluate is directly injected onto an Ultrasphere C-18 high-performance liquid chromatography column with quantification at 340 nm. No evaporation-concentration steps are necessary. Recoveries (extraction) of gabapentin and the internal standard are 94.2 +/- 2.9% and 98 +/- 2.0%, respectively. Analytical responses are linear from lower limit of sensitivity of 0.05 mg/L up to at least 10 mg/L. Between-run coefficients of variation (CV) range from 2.3 to 2.9% through the concentration range 0.5-4.0 mg/L. To illustrate the rationale for selection of test parameters for a robust method, we present optimization graphs for these processes. Moreover, we discuss the advantage of the packed cartridge and membrane sorbens as companion extraction devices.

Human RanGTPase-activating protein RanGAP1 is a homologue of yeast Rna1p involved in mRNA processing and transport

RanGAP1 is the GTPase activator for the nuclear Ras-related regulatory protein Ran, converting it to the putatively inactive GDP-bound state. Here, we report the amino acid sequence of RanGAP1, derived from cDNA and peptide sequences. We found it to be homologous to murine Fug1, implicated in early embryonic development, and to Rna1p from Saccharomyces cerevisiae and Schizosaccharomyces pombe. Mutations of budding yeast RNA1 are known to result in defects in RNA processing and nucleocytoplasmic mRNA transport. Concurrently, we have isolated Rna1p as the major RanGAP activity from Sc. pombe. Both this protein and recombinant Rna1p were found to stimulate RanGTPase activity to an extent almost identical to that of human RanGAP1, indicating the functional significance of the sequence homology. The Ran-specific guanine nucleotide exchange factor RCC1 and its yeast homologues are restricted to the nucleus, while Rna1p is reported to be localized to the cytoplasm. We suggest a model in which both activities, nuclear GDP-to-GTP exchange on Ran and cytoplasmic hydrolysis of Ran-bound GTP, are essential for shuttling of Ran between the two cellular compartments. Thus, a defect in either of the two antagonistic regulators of Ran would result in a shutdown of Ran-dependent transport processes, in agreement with the almost identical phenotypes described for such defects in budding yeast.

Isolation of human NuMA protein

NuMA is a protein involved in maintenance of nuclear structure and in the assembly of the mitotic spindle. Expression of amino-terminal deletion mutants results in a phenotype identical to that caused by a temperature-sensitive defect of RCC1 (regulator of chromosome condensation). Here we describe the isolation of NuMA protein from HeLa cells under mild conditions as a prerequisite to study its interactions with elements of the RCC1-Ran regulatory pathway. In an overlay assay, NuMA did not bind Ran.[gamma-32P]GTP. Thus it is clearly different from Ran.GTP binding proteins of similar M(r).

[Quantitative prognosis of mortality in newborn infants treated with artificial respiration]

Among the 5 indexes to estimate the mortality rate of ventilated newborns the alveolar-arterial oxygen gradient was elaborated as the best statistical model. By means of the probit method a quantitative estimation regarding mortality prognosis became possible. We could demonstrate that already mean values of the first 6 hours are able to give a very precise prognosis of mortality. Among the variables considered, a reduction of gestational age demonstrated a significant influence on the mortality rate. In contrary diagnoses of respiratory problems showed no influence. An increase in D(Aa)O2 raised mortality rate significantly. Using the D(Aa)O2-model the individual mortality rate for any ventilated newborn within an interval of (0.1) can be given.

Complete amino acid sequence of beta-tubulin from porcine brain

The primary structure of porcine brain beta-tubulin was determined by automated and manual Edman degradation of six sets of overlapping peptides. The protein consists of 445 amino acid residues and has a minimum of six positions that are heterogeneous, indicating at least two beta-tubulins in porcine brain. Comparison of the optimally aligned sequences of alpha-tubulin and beta-tubulin indicates that 41% of their primary structures are identical. A region rich in glycyl residues is similar both in sequence and predicted secondary structure to the phosphate binding loop of several nucleotide binding enzymes. beta-Tubulin contains a highly acidic COOH-terminal region that resembles the NH2-terminus of troponin T.

Complete amino acid sequence of alpha-tubulin from porcine brain

The amino acid sequence of alpha-tubulin from porcine brain was determined by automated and manual Edman degradation of eight sets of overlapping peptides. It comprises 450 residues plus a COOH-terminal tyrosine that is present only in 15% of the material. A region of 40 residues at the COOH-terminus is highly acidic, mainly due to 16 glutamyl residues. This high concentration of negative charge suggests a region for binding cations. At least six positions, most of them around position 270, are occupied by two amino acid residues each. Several of these exchange sites were assigned to specific peptides by analysis of the purified corresponding fragments. These data indicate four alpha-tubulins in porcine brain. Although alpha-tubulin on the whole is unrelated to other proteins, there are regions that can be correlated to sequences of the myosin head, to actin, to tropomyosin, and to troponins C and T.