Differential distribution of calcium stores in Paramecium cells : occurrence of a subplasmalemmal store with a calsequestrin-like protein (original) (raw)
Related papers
THE Ins(1,4,5)P3-Sensitive Ca2+ Store of Non-Muscle Cells: Endoplasmic Reticulum or Calciosomes?
The Journal of Experimental Biology, 1988
The binding of a number of extracellular ligands (hormones, growth factors, neurotransmitters etc.) to their plasma membrane receptors causes hydrolysis of phosphatidylinositol bisphosphate to initiate the formation of two second messengers, inositol 1,4,5-trisphosphate [Ins(l,4,5)/> 3 ] and diacylglycerol, DAG. DAG has been shown to activate protein kinase C, whereas Ins(l,4,5)/) 3 induces the release of Ca 2+ from an intracellular pool. This rapidly mobilizable, Ins(l,4,5)/> 3sensitive Ca 2+ store has until now been identified as the endoplasmic reticulum, ER. We demonstrate that this is untenable and provide evidence for the existence of an unrecognized organelle, the 'calciosome'. This conclusion is based on the following experimental evidence. (1) There is no correlation between the abundance of ER and the amount Ins(l,4,5)F 3-sensitive Ca 2+ release. (2) There is no correlation between ER markers and those for the Ca 2+ store [Ins(l,4,5)F 3 binding and sensitivity, Ca 2+ uptake]. (3) A protein similar to striated muscle calsequestrin, CS, has been identified in microsomal fractions from a number of tissues; it copurifies with markers of the Ca 2+ store, but not with those of ER. (4) Subcellular localization of the CS-like protein by electron microscopy reveals that in all cells so far analysed this protein is localized in small, membraneenclosed structures, calciosomes, which are also stained by an anti-Ca 2+-ATPase antibody. Calciosomes appear to be morphologically distinct from any other known cell organelle. (5) Although they stain different portions of the calciosomes (membrane and lumen, respectively), anti-Ca 2+-ATPase and anti-CS antibodies do not recognize any antigen in ER cysternae; antibodies directed against known components of ER do not bind to calciosomes.
Biochimica et Biophysica Acta (BBA) - Biomembranes, 1989
The 55-kDa hlgh-~finity calcium binding protein (HAC~P) was first ~dentff|ed and isolated item skeletal muscle sarcoplasmic retlealum (SR) Using polydonal anlibodies raised against the HACBP ,~lated from skelelal muscle we have identified this protein in cardiac and smooth muscle as well as in non-muscle cells. Allh0egh the 5~-kDa protein has a size, properties a~3d IocalizaUon simdar to that of calsequeslrin, the two proteins are tmmmm~ogieally d~sfim-'t. The NHz-terminal sequence el uterine HACBP is also completely different from that of ,.al.,,equest~-in but it is identical to that of rmbbit liver calmgulln, u reeendy identified oak|urn binding protein lnd,rect ,mm.tmed[luereseenee s~in|n~ of frozen sections and culture eeUs from • ~ariety of tissues slmws that the 5S-kDa protein [oc~[zes ~dolahmn~y to junctional SR and T-tulle meas in skdetal m~le, to SR in smoolh and cardiac muscle cells, and to ER in a variety of non-muscle cells These data show tbat the i~rotein is present in a withe variety of nssues and suggest that ~t is a protein common re, ~h s~rcoplasmie and endol#asm~c ~eticulm~ memlwanes.
Interactions of calreticulin with proteins of the endoplasmic and sarcoplasmic reticulum membranes
FEBS Letters, 1993
The ability of ['Z51]calreticulin to bind to membrane fractions isolated from different muscle and non-muscle tissues was examined by a protem overlay technique. Specific ['251]calreticulin binding proteins were detected in rat liver smooth and rough endoplasmic reticulum and Golgi, in canme pancreatic microsomes, and in rabbit skeletal muscle sarcoplasmic reticulum. These proteins were confined only to membranes that contam calreticulin; they were not found in rat liver mitochondria or cytosol. ['2SI]Calreticulin binds to a 50-kDa protein and a number of lower M, (20,000-38,000) endoplasmic reticulum membrane proteins and to 30-kDa protein in skeletal muscle sarcoplasmic reticulum. Full-length calrettculin and the carboxyl-terminal region (C-domain) of the protein both competed with ["51]calreticulin for binding to the membrane proteins. Bmdmg of ['2SI]calreticulin to pancreatic microsomes was also partially inhibited by the N-domam and to a lesser extent by the P-domurn of the protein.
The Ins (1, 4, 5) P3-sensitive Ca2+ store of non-muscle cells: endoplasmic reticulum or calciosomes?
1988
The binding of a number of extracellular ligands (hormones, growth factors, neurotransmitters etc.) to their plasma membrane receptors causes hydrolysis of phosphatidylinositol bisphosphate to initiate the formation of two second messengers, inositol 1,4,5-trisphosphate [Ins(l,4,5)/> 3 ] and diacylglycerol, DAG. DAG has been shown to activate protein kinase C, whereas Ins(l,4,5)/) 3 induces the release of Ca 2+ from an intracellular pool. This rapidly mobilizable, Ins(l,4,5)/> 3sensitive Ca 2+ store has until now been identified as the endoplasmic reticulum, ER. We demonstrate that this is untenable and provide evidence for the existence of an unrecognized organelle, the 'calciosome'. This conclusion is based on the following experimental evidence. (1) There is no correlation between the abundance of ER and the amount Ins(l,4,5)F 3-sensitive Ca 2+ release. (2) There is no correlation between ER markers and those for the Ca 2+ store [Ins(l,4,5)F 3 binding and sensitivity, Ca 2+ uptake]. (3) A protein similar to striated muscle calsequestrin, CS, has been identified in microsomal fractions from a number of tissues; it copurifies with markers of the Ca 2+ store, but not with those of ER. (4) Subcellular localization of the CS-like protein by electron microscopy reveals that in all cells so far analysed this protein is localized in small, membraneenclosed structures, calciosomes, which are also stained by an anti-Ca 2+-ATPase antibody. Calciosomes appear to be morphologically distinct from any other known cell organelle. (5) Although they stain different portions of the calciosomes (membrane and lumen, respectively), anti-Ca 2+-ATPase and anti-CS antibodies do not recognize any antigen in ER cysternae; antibodies directed against known components of ER do not bind to calciosomes.
Cell Calcium, 1989
Calclosomes are intracellular organelles in HL-60 cells, neutrophils and various other cell types, characterized by their content of a Ca*+-binding protein that is biochemically and immunologically similar to calsequestrin (CS) from muscle cells. In subcellular fractionation studies the CS-like protein copurlfles with functional markers of th$!nosltol 1,4,Mrlsphosphate (II") releasable Ca*+-store. These markers (ATPdepeWM Ca -uptake and IPpinduced Ca -release) show a subcellular distrlbutlon which is cfearly distinct from the endoplasmic reticulum and other organelles. In morphological studies, antibodiee against rabbit skeletal muscle CS protein specifically stalned hhherto unrecognized vesicles wlth a dlameter between 50 and 250 nm. Thus both, blochemkral and morphological studies indicate that the calsequestrin containing intracellular C%?t-store, now referred to as the calciosome, is distinct from other known orgarNes such as endoplasmic reticulum. Calciosomes are likely to play an important role in lntmceltular Ca*+-homeostasis. They are possibly the intracellular target of lnosftol 1,4,!%trfsphosphate and thus the source of Ca*+ that is redistributed into the cytosol following surface receptor activation in non-muscle cells.
1988
Calsequestrin (CS) is the protein responsible for the high-capacity, moderate affinity binding of Ca2+ within the terminal cisternae of the sarcoplasmic reticulum, believed up to now to be specific for striated muscle. The cells of two nonmuscle lines (HL-60 and PC12) and of two rat tissues (liver and pancreas) are shown here to express a protein that resembles CS in many respects (apparent mass and pH-dependent migration in NaDodSO4/PAGE; blue staining with StainsAll dye; Ca2`binding ability) and is specifically recognized by afflinity-purified antibodies against skeletal mus
A procedure was developed for the isolation of reticuloplasm, the luminal material of the endo-plasmic reticulum (ER). A reticuloplasm-rich extract was prepared from a murine plasmacytoma cell line that contains large amounts of ER, by first extracting the cytoplasmic contents using hypotonic lysis to yield ER-rich 'shells' followed by mechanical lysis to release the ER contents. The extract contains five major proteins with apparent molecular weights of 100, 75, 60, 58 and 55 (xlO 3)M r by SDS— polyacrylamide gel electrophoresis. The 100, 75 and 58 (Xl0 3)M r species were identified as the known ER proteins endoplasmin, BiP and PD1, respectively. The ER association of the 60 and 55 (X10 3) M r proteins was confirmed by conf ocal fluor-escence microscopy with affinity-purified anti-bodies. Equilibrium dialysis with isolated reticuloplasm gave a calcium-binding capacity of 300 nmoles calcium per mg protein with half-maximal binding at 3 mM-Ca 2+. Purified endoplasmin bound 280 nmoles calcium per mg protein at a calcium concentration of 5mM-Ca 2+. A calcium overlay test revealed that, in addition to endoplasmin, reticuloplasm contained at least three other calcium-binding proteins: i.e. BiP, PDI and the 55xlO 3 M r protein, respectively, with endoplasmin and the 5 5 x 1 0 ^ , protein (CRP55) accounting for the major proportion of the calcium-binding activity. Treatment of cells with calcium ionophore led to the specific over-expression of the major calcium-binding reticuloplasmins endoplasmin, BiP and CRP55. These studies show that the lumen of the ER contains a family of proteins with the capacity to bind significant amounts of calcium in the millimo-lar range and thereby to confer upon the ER the ability to perform a calcium storage function analogous to that of the sarcoplasmic reticulum in muscle cells.
The Journal of biological chemistry, 1988
Rat liver endoplasmic reticulum (ER) membranes were investigated for the presence of proteins having structural relationships with sarcoplasmic reticulum (SR) proteins. Western immunoblots of ER proteins probed with polyclonal antibodies raised against the 100-kDa SR Ca-ATPase of rabbit skeletal muscle identified a single reactive protein of 100 kDa. Also, the antibody inhibited up to 50% the Ca-ATPase activity of isolated ER membranes. Antisera raised against the major intraluminal calcium binding protein of rabbit skeletal muscle SR, calsequestrin (CS), cross-reacted with an ER peptide of about 63 kDa, by the blotting technique. Stains-All treatment of slab gels showed that the cross-reactive peptide stained metachromatically blue, similarly to SR CS. Two-dimensional electrophoresis (Michalak, M., Campbell, K. P., and MacLennan, D. H. (1980) J. Biol. Chem. 255, 1317-1326) of ER proteins showed that the CS-like component of liver ER, similarly to skeletal CS, fell off the diagonal ...