Cloning of the C-terminal cytoplasmic fragment of the tar protein and effects of the fragment on chemotaxis of Escherichia coli

A gene encoding only the C-terminal portion of the receptor-transducer protein Tar of Escherichia coli was constructed. The gene product was detected and localized in the cytoplasmic fraction of the cell by immunoblotting with anti-Tar antibodies. The C-terminal fragments from wild-type and mutant tar genes were characterized in vivo. The C-terminal fragment generated from tar-526, a mutation that results in a dominant "tumble" phenotype, was found to be deamidated and methylated by the CheB and CheR proteins, respectively. The C-terminal fragment derived from a wild-type gene was poorly deamidated, and the C-terminal fragment derived from tar-529, a dominant mutant with a "smooth swimming" phenotype, was not apparently modified. Cells carrying the C-terminal fragment with the tar-526 mutation as the sole receptor-transducer protein showed a high frequency of tumbling and chemotaxis responses to changes in intracellular pH. These results suggest that the cytoplasmic C-terminal fragment of Tar retains some of the functions of the whole protein in vivo

The teneurin C-terminal domain possesses nuclease activity and is apoptogenic.

Teneurins are type 2 transmembrane proteins expressed by developing neurons during periods of synaptogenesis and apoptosis. Neurons expressing teneurin-1 synapse with other teneurin-1-expressing neurons, and neurons expressing teneurin-2 synapse with other teneurin-2-expressing neurons. Knockdowns and mutations of teneurins lead to abnormal neuronal connections, but the mechanisms underlying teneurin action remain unknown. Teneurins appear to have evolved via horizontal gene transfer from prokaryotic proteins involved in bacterial self-recognition. The bacterial teneurin-like proteins contain a cytotoxic C-terminal domain that is encapsulated in a tyrosine-aspartic acid repeat barrel. Teneurins are likely to be organized in the same way, but it is unclear if the C-terminal domains of teneurins have cytotoxic properties. Here we show that expression of teneurin C-terminal domains or the addition of purified teneurin C-terminal domains leads to an increase in apoptosis in vitro The C-terminal domains of teneurins are most similar to bacterial nucleases, and purified C-terminal domains of teneurins linearize pcDNA3 and hydrolyze mitochondrial DNA. We hypothesize that yet to be identified stimuli lead to the release of the encapsulated teneurin C-terminal domain into the intersynaptic region, resulting in programmed cell death or the disruption of mitochondrial DNA and the subsequent pruning of inappropriate contacts

Iron-binding fragments from the N-Terminal and C-Terminal regions of human lactoferrin

Digestion of lactoferrin with pepsin at pH 3.0 gave an iron-binding half-molecule that represents the C-terminal part of the native protein. Tryptic or chymotryptic digestion of 30%/-iron-saturated lactoferrin yielded the N- and C-terminal half molecules, which could be separated by DEAE-Sephadex chromatography. The N- and C-terminal fragments did not show any immunological cross-reaction. The carbohydrate of lactoferrin was distributed equally between the two fragments

FGF23 metabolism, a new paradigm for chronic kidney disease

Introduction:  Fibroblast growth factor-23 (FGF23) is a major regulator of phosphate metabolism often elevated in genetic hypophosphataemic disorders and in chronic kidney disease. Recent studies have identified relationships between FGF23 and various markers of iron status including ferritin. New assays measuring the intact form of FGF23 have been released.  Objective:  To determine the relationship between ferritin and C-terminal and intact FGF23 concentrations in blood.  Method:  FGF23 concentrations were measured using the 2nd generation, two-site enzyme-linked immunosorbent assay for either C-terminal or intact FGF23 (Immutopics Inc., Ca, USA). Ferritin was measured on a COBAS 6000 (Roche Diagnostics). Assay accuracy and precision were monitored using kit controls supplied by the manufacturers.  Results:  We observe a weak negative correlation between measurements of C-terminal and intact FGF23 (Pearson’s rho=0.85 p<0.0001). We observed no statistically significant correlation of ferritin concentrations with either FGF23 C-terminal or intact. However high concentrations of ferritin were observed in samples showing low concentrations of C-terminal FGF23 (<140RU/mL) and intact FGF23 (<122pg/mL).  Conclusion:  Although not statistically significant, we observe a negative relationship between concentrations of ferritin and FGF23. High level of C-terminal FGF23 is found in patients with chronic kidney disease, especially in patients with end-stage renal disease usually regarded as a compensatory response to hyperphosphatemia or phosphate overload. We observed a cluster of patients with retention of both C-terminal and intact FGF23 associated with low levels of ferritin suggesting that metabolism and/or excretion of FGF23 in CDK patients might be an iron dependent mechanism

SPAN C - Terminal sterilization process analysis program

Computer program, SPAN-C, measures the dry heat thermal sterilization process applied to a planetary capsule and calculates the time required for heat application, steady state conditions, and cooling. The program is based on the logarithmic survival of micro-organisms. Temperature profiles must be input on cards

Water immersion increases the concentration of the immunoreactive N-terminal fragment of pro-atrial natriuretic factor in human plasma

Atrial natriuretic factor (ANF) N-terminal (ANF 1–98) and C-terminal (ANF 99–126) fragments were determined by radioimmunoassay in human plasma. Mean basal plasma ANF N-terminal concentrations in 9 healthy subjects were 461 ± 58 fmol/ml,significantly (p<0.0001) higher than ANF C-terminal concentrations ( 4.8 ± 0.5 fmol/ml). Central volume stimulation by one hour head-out water immersion (WI) induced a significant (p<0.01) increase of the C-terminal peptide levels to 11.6 ± 2.3 fmol/ml,paralleled by a significant (p<0.001) increase of the N-terminal fragment levels to 749 ± 96 fmol/ml. Increases of plasma concentrations of both fragments upon WI correlated significantly (r=0.71;p<0.05). These data suggest cosecretion of the N-terminal fragment with the C-terminal fragment of pro ANF 1–126 following a physiological stimulus of ANF release in man

Role of the liver in splanchnic extraction of atrial natriuretic factor in the rat

Mesenteric, hepatic and splanchnic extraction of C-terminal and N-terminal atrial natriuretic factor was investigated in male Sprague-Dawley rats. Plasma concentrations (mean ± S.E.M.) of C-terminal atrial natriuretic factor were 55.0 ± 6.1 fmol/ml, 31.2 ± 4.0 fmol/ml and 23.5 ± 3.3 fmol/ml (n = 12) in the abdominal aorta, the portal vein and the hepatic vein, respectively. N-terminal atrial natriuretic factor plasma levels in these vessels were 3031 ± 756 fmol/ml, 2264 ± 661 fmol/ml and 1618 ± 496 fmol/ml (n = 6), respectively. Although the mesenteric extraction ratio was higher (p < 0.05) for C-terminal atrial natriuretic factor (42% ± 6%) than for N-terminal atrial natriuretic factor (28% ± 4%), there were no significant differences in the hepatic extraction ratio (41% ± 5% vs. 39% ± 6%) and the splanchnic extraction ratio (56% ± 5% vs. 50% ± 7%). These data suggest a major role of the liver in the splanchnic extraction of C-terminal and of N-terminal atrial natriuretic factor in the rat. (HEPATOLOGY 1992;16:790-793

Alternative Splicing and Polyadenylation Contribute to the Generation of hERG1 C-terminal Isoforms

The human ether-a-go-go-related gene 1 (hERG1) encodes the pore-forming subunit of the rapidly activating delayed rectifier potassium channel. Several hERG1 isoforms with different N- and C-terminal ends have been identified. The hERG1a, hERG1b, and hERG1-3.1 isoforms contain the full-length C terminus, whereas the hERG1USOisoforms, hERG1aUSO and hERG1bUSO, lack most of the C-terminal domain and contain a unique C-terminal end. The mechanisms underlying the generation of hERG1USOisoforms are not understood. We show that hERG1 isoforms with different C-terminal ends are generated by alternative splicing and polyadenylation of hERG1 pre-mRNA. We identified an intrinsically weak, noncanonical poly(A) signal, AGUAAA, within intron 9 of hERG1 that modulates the expression of hERG1a and hERG1aUSO. Replacing AGUAAA with the strong, canonical poly(A) signal AAUAAA resulted in the predominant production of hERG1aUSO and a marked decrease in hERG1 current. In contrast, eliminating the intron 9 poly(A) signal or increasing the strength of 5′ splice site led to the predominant production of hERG1a and a significant increase in hERG1 current. We found significant variation in the relative abundance of hERG1 C-terminal isoforms in different human tissues. Taken together, these findings suggest that post-transcriptional regulation of hERG1 pre-mRNA may represent a novel mechanism to modulate the expression and function of hERG1 channels

The PET and LIM1-2 domains of testin contribute to intramolecular and homodimeric interactions

The focal adhesion protein testin is a modular scaffold and tumour suppressor that consists of an N-terminal cysteine rich (CR) domain, a PET domain of unknown function and three C-terminal LIM domains. Testin has been proposed to have an open and a closed conformation based on the observation that its N-terminal half and C-terminal half directly interact. Here we extend the testin conformational model by demonstrating that testin can also form an antiparallel homodimer. In support of this extended model we determined that the testin region (amino acids 52-233) harbouring the PET domain interacts with the C-terminal LIM1-2 domains in vitro and in cells, and assign a critical role to tyrosine 288 in this interaction