Plasma membranes from intestinal microvilli and erythrocytes contain cytochromes b5 and P-420.
Biochim Biophys Acta
; 600(3): 739-55, 1980 Aug 14.
Article
em En
| MEDLINE
| ID: mdl-7407143
ABSTRACT
The presence of cytochromes b5, P-450 and P-420 and activities of NADH- and NADPH-cytochrome c redutases were determined in plasma membranes isolated from microvilli of the chick and rat intestinal epithelium and erythrocyte membranes from chick, rat and man. The results are compared with the amounts of these components found in microsomal fractions from intestinal epithelium and in nuclear membranes from chick erythrocytes. Plasma membranes from intestinal microvilli and from erythrocytes contained significant amounts of NADH-cytochrome c reductase activity and of a pigment spectrophotometrically indistinguishable from rat liver microsomal cytochrome b5. In addition, cytochrome b5 fragments were prepared from the membranes by limited trypsin digestion and consisted of two to four components with Mr values in the range 10 000-13 500. In low-temperature difference spectra, the presence of a second cytochrome was noted which was similar to cytochrome P-420. Cytochrome P-450 and NADPH-cytochrome c reductase activities were not detected in plasma membrane fractions in significant concentrations but were present in the corresponding endomembrane fractions. These findings in highly purified, well defined plasma membrane fractions, in which contamination by endomembranes is minimal, strengthen the evidence for the existence of cytochrome-containing redox systems in plasma membranes of various cells and suggest that such redox components are general components of the cell surface. Possible functions and origins of these redox components in plasma membranes are discussed.
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Bases de dados:
MEDLINE
Assunto principal:
Membrana Celular
/
Citocromos
/
Membrana Eritrocítica
/
Eritrócitos
/
Intestino Delgado
/
Microvilosidades
Limite:
Animals
/
Female
/
Humans
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
1980
Tipo de documento:
Article