scholarly journals The predominant calcimedins from Trypanosoma brucei comprise a family of flagellar EF-hand calcium-binding proteins

1992 ◽  
Vol 287 (1) ◽  
pp. 187-193 ◽  
Author(s):  
Y Wu ◽  
N G Haghighat ◽  
L Ruben
Keyword(s):  
Trypanosoma Brucei ◽  
Calcium Binding ◽  
Binding Proteins ◽  
Immunoblot Analysis ◽  
Cross Reactivity ◽  
Calcium Binding Proteins ◽  
Phospholipid Vesicles ◽  
Ef Hand ◽  
Sequence Similarities ◽  
Binding Loop

The cellular complement of calcimedins was identified in Trypanosoma brucei by Ca(2+)-dependent association with phenyl-Sepharose. Predominant calcimedins with molecular mass of 23-26 kDa and 44 kDa, along with minor calcimedins of 96, 120 and 230 kDa, were obtained. The trypanosome calcimedins were unrelated to vertebrate annexins, based upon antibody cross-reactivity and an inability to associate in a Ca(2+)-dependent way with phospholipid vesicles comprised of phosphatidylserine or phosphatidylethanolamine/phosphatidylcholine (1:1, w/w). Partial sequence analysis demonstrated that 44 kDa calcimedin (Tb-44) contained an EF-hand calcium-binding loop. Five CNBr/tryptic fragments exhibited a total of 93% similarity with Tb-17, a 23 kDa EF-hand protein in T. brucei. The trypanosome calcimedins appeared to comprise a family of proteins, based on sequence similarities and antibody cross-reactivity of affinity-purified anti-Tb44 with the 23-26 kDa cluster. No evidence was found for Tb-44 in the related species T. cruzi, Leishmania taraentolae or Crithidia fasciculata. Antibodies against Tb-44 were localized by immunofluorescence along the flagellum of T. brucei. Immunoblot analysis of flagella-enriched preparations demonstrated that Tb-44 and the 23-26 kDa cluster were present in this structure. We conclude that annexin family members are not among the predominant trypanosome proteins that associate with phenyl-Sepharose in a Ca(2+)-dependent way. Instead, the major trypanosome calcimedins comprise a family of flagellar EF-hand calcium-binding proteins.

A change-in-hand mechanism for S100 signalling

1998 ◽  
Vol 76 (2-3) ◽  
pp. 324-333 ◽  
Author(s):  
Steven P Smith ◽  
Gary S Shaw
Keyword(s):  
Conformational Change ◽  
Calcium Ion ◽  
Calcium Binding ◽  
Binding Proteins ◽  
Three Dimensional ◽  
Calcium Binding Proteins ◽  
C Terminus ◽  
Ef Hand ◽  
Sensor Proteins ◽  
Binding Loop

S100 proteins are a group of small dimeric calcium-binding proteins making up a large subclass of the EF-hand family of calcium-binding proteins. Members of this family of proteins have been proposed to act as intracellular calcium modulatory proteins in a fashion analogous to that of the EF-hand sensor proteins troponin-C and calmodulin. Recently, NMR spectroscopy has provided the three-dimensional structures of the S100 family members S100A6 and S100B in both the apo- and calcium-bound forms. These structures have allowed for the identification of a novel calcium-induced conformational change termed the change-in-hand mechanism. Helix III of the C-terminal calcium-binding loop changes its helix-helix interactions (or handness) with the remainder of the molecule primarily owing to the reorientation of the backbone in an effort to coordinate the calcium ion. This reorientation of helix III exposes several residues in the C-terminus and linker regions of S100B resulting in the formation of a hydrophobic patch surrounded be a number of acidic residues. This site is the proposed region for protein-protein recognition.Key words: S100, calcium-binding protein, EF-hand, conformational change.

scholarly journals The gene family of EF-hand calcium-binding proteins from the flagellum of Trypanosoma brucei

1994 ◽  
Vol 304 (3) ◽  
pp. 833-841 ◽  
Author(s):  
Y Wu ◽  
J Deford ◽  
R Benjamin ◽  
M G Lee ◽  
L Ruben
Keyword(s):  
Amino Acid ◽  
Trypanosoma Brucei ◽  
Calcium Binding ◽  
Binding Proteins ◽  
Direct Repeat ◽  
Calcium Binding Proteins ◽  
Amino Acid Sequences ◽  
Reading Frame ◽  
Genomic Clones ◽  
Ef Hand

The flagellum of Trypanosoma brucei contains calmodulin, and a separate family of antigenically related EF-hand calcium-binding proteins which we call calflagins. The following study evaluates the structure and genomic organization of the calflagin family. Genomic Southern blots indicated that multiple copies of calflagin genes occurred in T. brucei, and that all of these copies were contained in a single 23 kb XhoI-XhoI fragment on chromosomes 15 and 16 mRNAs of 1.2 and 1.6 kb were identified in bloodstream and procyclic life-cycle stages. Genomic fragments of 2.5 and 1.7 kb were cloned that encoded calflagin sequences. The calflagin genes were arranged tandemly along the genomic fragments. Three new members of the calflagin family were sequenced from a cDNA clone and the two genomic clones. Two unrelated families of 3′ flanking sequences were downstream from the calflagin genes. An open reading frame that was unrelated to any calflagin sequence was at the 5′ end of the 2.5 kb genomic fragment. The deduced amino acid sequences of the genomic clones (called Tb-24 and Tb-1.7g) were similar to the previously described Tb-17. Each encoded an approximately 24 kDa protein which contained three EF-hand calcium-binding motifs and one degenerate EF-hand motif. The cDNA encoded a protein (called Tb-44A) which was approximately twice as large as the other calflagins. The large size resulted from a nearly direct repeat of 186 amino acids. In general, variability among the T. brucei calflagins was greater than observed for related proteins from Trypanosoma cruzi. We demonstrate that this variability resulted from amino acid substitutions at the N-terminus, C-terminal extensions, and duplication of internal segments.

scholarly journals S100A14, a Member of the EF-hand Calcium-binding Proteins, Is Overexpressed in Breast Cancer and Acts as a Modulator of HER2 Signaling

2013 ◽  
Vol 289 (2) ◽  
pp. 827-837 ◽  
Author(s):  
Chengshan Xu ◽  
Hongyan Chen ◽  
Xiang Wang ◽  
Jidong Gao ◽  
Yiqun Che ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Calcium Binding ◽  
Binding Proteins ◽  
Calcium Binding Proteins ◽  
Ef Hand ◽  
Her2 Signaling

Vitamin D independence of small calcium-binding proteins in nonclassical target tissues

1991 ◽  
Vol 260 (5) ◽  
pp. E794-E800
Author(s):  
M. R. Walters ◽  
M. E. Bruns ◽  
R. M. Carter ◽  
P. C. Riggle
Keyword(s):  
Vitamin D ◽  
Rat Brain ◽  
Blot Analysis ◽  
Calcium Binding ◽  
Binding Proteins ◽  
Immunoblot Analysis ◽  
Calcium Binding Proteins ◽  
Northern Analysis ◽  
Dihydroxyvitamin D3 ◽  
Low Levels

The presence and regulation of Ca-binding proteins (CaBPs) were investigated in newly identified 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] target tissues. 45Ca(2+)-blot analysis of proteins in normal rats yielded a 45Ca2+ band comigrating with authentic calmodulin. Additionally, a parvalbumin-like band (mol mass = 15.4 +/- 0.3 kDa) was prominent in prostate, and a strong unidentified 45Ca2+ band was always evident in the testis (mol mass = 23.5 +/- 0.7 kDa). Lung, bladder, and especially prostate demonstrated 45Ca2+ bands comigrating with the intestinal vitamin D-related CaBP (CaBP-D9K; mol mass = 10.9 +/- 0.5 kDa). Most tissues (including testis, heart, and lung) exhibited low levels of a 45Ca2+ band comigrating with the renal CaBP-D28K (mol mass = 28.3 +/- 0.4 kDa). Importantly, 45Ca2+ binding to all detectable CaBPs was unchanged in these four tissues in vitamin D-deficient rats, despite substantial downregulation of the intestinal CaBP-D9K and renal CaBP-D28K. Neither immunoblot analysis (rabbit anti-rat renal CaBP-D28K) nor Northern analysis (rat brain CaBP-D28K cDNA) provided evidence for coidentity of the 28-kDa 45Ca2+ band with the CaBP-D28K. Conversely, immunoblot analysis of lung, but not prostate, cytosol provided evidence for specific immunocross-reactivity to rabbit anti-rat intestinal CaBP-D9K. Immunoblot analysis of the 9-kDa CaBP in lung further confirmed its vitamin D independence. In conclusion, the vitamin D independence of the CaBPs in these putative new 1,25(OH)2D3 targets suggests the absence of an obligatory relationship between 1,25(OH)2D3 effects and CaBP induction therein.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Calciomics: prediction and analysis of EF-hand calcium binding proteins by protein engineering

2010 ◽  
Vol 53 (1) ◽  
pp. 52-60 ◽  
Author(s):  
YanYi Chen ◽  
ShengHui Xue ◽  
YuBin Zhou ◽  
Jenny Jie Yang
Keyword(s):  
Protein Engineering ◽  
Calcium Binding ◽  
Binding Proteins ◽  
Calcium Binding Proteins ◽  
Ef Hand
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