摘要:

AbstractThe hypothesis of a correlation between the effects of temperature on red blood cells hypotonic hemolysis and hypertonic cryoheniolysis and two thermotropic structural transitions evidenced by EPR studies has been tested. Hypertonic cryoheniolysis of red blood cells shows critical temperatures at 7°C and 19°C. In hypotonic solution, the osmotic resistance increases near 10°C and levels off above 20°C. EPR studies of red blood cell membrane of a 16‐dinyloxyl stearic acid spin label show, in the 0–50°C range, the presence of three thermotropic transitions at 8, 20, and 40°C. Treatments of red blood cells with acidic or alkaline pH, glutaraldehyde, and chlorpromazine abolish hypertonic cryoheniolysis and reduce the effect of temperature on hypotonic hemolysis. 16‐Dinyloxyl stearic acid spectra of red blood cells treated with glutaraldehyde and chlorpromazine show the disappearance of the 8°C transition. Both the 8°C and the 20°C transitions were abolished by acidic pH treatment. The correlation between the temperature dependence of red blood cell lysis and thermotropic breaks might be indicative of the presence of structural transitions producing areas of mismatching between differently ordered membrane components where the osmotic resistanc

ISSN:0730-2312    

DOI:10.1002/jcb.240250202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThe relationship between membrane structural properties and functions has been generally inferred from observed thermotropic phenomena. By the use of 16‐dinyloxyl stearic acid spin probe we investigated the red blood cell membrane components involved in three characteristic thermotropic structural transitions occurring at 8, 20, and 40°C. The transition at 8°C is removed by chymotrypsin treatment at the cytoplasmic membrane layer. The 20°C phase transition is unmodified after chymotrypsin treatment and occurs at 15°C after complete proteolysis of intramembranc chymolrypsin insensitive peptides. Liposomes from the total lipid extract of RBC show only one thermotropic transition at 15°C. The 40°C phase transition is absent in vesicles free of skeletal proteins, in vesicles obtained after RBC storage, and in low‐ionic‐strength resealed ghosts. Transitions at 8°C and 40°C appear to be due to the interactions of cytoplasmic exposed proteins with membrane, whereas the 20°C transition is intrinsic to the l

ISSN:0730-2312    

DOI:10.1002/jcb.240250203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThe lipid requirements of a human macrophagelike cell line were studied. The cells grew only about one generation in a medium supplemented with delipidated serum; during the growth the cholesterol content of the cells was depleted. Growth was restored by including in the medium serum lipids subjected to alkaline hydrolysis or cholesterol. The extent of growth was dependent on cholesterol concentration. No growth was obtained with 5‐cholestene, 5‐cholesten‐3‐one, cholesteryl chloride, coprostanol, β‐sitosterol, orstigmasterol. Very limited growth occurred with cholesterol methylether, epicholesterol, or β‐cholestarol. Therefore, for optimal growth of these cells there is a stringent requirement for the structural features of cholesterol, which include a 3‐βOH group, a Δ5‐double bond, atransring A/B configuration, and freedom of the side chain from bulky groups. This stringency far exceeds what was previously reported for other cells. Of the six sterols that failed to support growth at all, five were incorporated into cells moderately to extensively. This suggests that assembly of a functional membrane is impaired when these sterols are used as su

ISSN:0730-2312    

DOI:10.1002/jcb.240250204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractA calmodulin acceptor protein has been identified in isolated hamster caudal sperm by immunofluoresence and Western transfer techniques. The protein shows a localization in sperm heads identical to calmodulin. Fluorescence of both calmodulin and the acceptor protein are lost by treatment with MgCl2, conditions which release the acrosome. These results are consistent with the proposed function of calmodulin in a sperm function.

ISSN:0730-2312    

DOI:10.1002/jcb.240250205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractTwo monoclonal antibodies that cause changes in the morphology of cultured chick myogenic cells have been described previously [8]. In this paper, these antibodies are shown to interact with the same 140Kd protein. The 140Kd protein has been further characterized as a cell‐surface glycoprotein by lactoperoxidase‐catalyzed iodinations and lectin affinity chromatography. The protein is resistant to digestion by trypsin and collagenase and has been shown to be unrelated to fibronectin by immunoprecipitation studies and by peptide mapping. A second protein, of approximately 170Kd MW; is also immunoprecipitated by the monoclonal antibodies. This protein is probably unrelated to the 140Kd protein since the peptide maps are quite disti

ISSN:0730-2312    

DOI:10.1002/jcb.240250206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

ISSN:0730-2312    

DOI:10.1002/jcb.240250201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY