The occurrence of cytochromes in the membranous structures of calf thymus nuclei

Structures and Functions of the Nuclear Envelope

“…Furthermore, gel electrophoretic protein patterns of both membrane fractions show marked homologies, though some bands are specmc for the one or the other Deumling, 1972;Monneron et al, 1972; for detailed discussion see Chapter 6). The same cytochrome pigments have been found in both fractions, although their relative content was _ found to be somewhat lower, on a protein weight basis, in the nuclear membranes (Ueda et al, 1969;Franke et al, 1970;Crane, 1971, 1972;Fleischer et al, 1971;Kasper, 1971;Ichikawa and Mason, 1973). Patterns of nuclear membrane-bound enzyme activities are also generally identical with those in rough microsomes (a vesicle fraction derived from the rough ER), although quantitative differences per protein mass have been reported: for instance, in mammalian liver the microsomal marker enzyme activities glucose-6-phosphatase and NADH-and NADPH-cytochrome C reductases have been reported to be lower in the nuclear membranes (Zbarsky et al, 1968Kashnig and Kasper, 1969;Berezney et al, 1970Franke et al, 1970;Kasper, 1971;Zentgraf et al, 1971;Ichikawa and Mason, 1973;Green and Dobrjansky, 1972;Kay et al, 1972;Kartenbeck et al, 1973;; for cytochemical references see further Goldfischer et al, 1964;Leskes and Siekevitz, 1969;Kartenbeck et al, 1973).…”

“…While the presence of nucleus-interior markers (e.g., pre-rRNA, specific DNA and RNA polymerases, NAD-pyrophosphorylase) can be assayed, the amount of microsomal contamination is hard to determine since an absolute marker substance discriminating between nuclear and microsomal membrane is not yet known (for controversial statements concerning the presence of NADH-cytochrome C-reductase and glucose-6-phosphatase in mammalian liver nuclear membranes, see Kashnig and Kasper, 1969;Zbarsky et al, 1969;Berezney et al, 1970Franke et al, 1970;Kasper, 1971;Kartenbeck et al, 1973; for details see Chapter 6). Membranolytic detergents have also been used in attempts to prepare nuclear membrane material, specifically for enrichment of inner nuclear membrane (Bach and Johnson, 1966;Whittle et al, 1968;Ueda et al, 1969;Ben-Porat and Kaplan, 1971). These seem to be of very limited value, since they induce varying amounts of structural damage .…”

Nuclear Membranes From Mammalian Liver

“…VoLumE 46, 1970 • pages [379][380][381][382][383][384][385][386][387][388][389][390][391][392][393][394][395] clear envelope fragments were isolated from mammalian liver first by the method of Franke (26,27) which uses a combination of hypotonic shock and sonication for the nuclear disruption (15,(26)(27)(28)(29)95) and, recently, by other authors employing similar methods (9, 43,97) . Other attempts for obtaining nuclear membrane material from diverse mammalian cells, such as HeLa cells, calf thymus, and rat liver, involved the use of detergents such as deoxycholate and Triton X-100 (4, 75,92,93) which obviously can cause considerable membrane dissociation and thus progressive loss of membrane material, especially in the outer nuclear membrane (40), and consequently have a very limited range of application .…”

The Nuclear Envelope in Freeze-Etching

“…In addition, the nuclear envelope shows various enzymatic differences to other cytomembranes and can even be distinguished from the ER, as has hitherto been established for diverse membrane-bound phosphohydrolases and redox activities, including the electron transfering pigments. This has been shown in particular with mammalian liver (Jarasch, 1969;Kashnig and Kasper, 1969;Kuzmina et al, 1969;Zbarsky et al, 1969;Berezney et al, 1970b;Franke et al, 1970;Kasper, 1971;Jarasch et al, 1971) and with the calf thymus (Ueda et al, 1969;Betel, 1970;Conover, 1970a and b;Reilly, 1971;Rupec and Sekeris, 1971). Peculiarities of the nuclear membrane enzymology have also been noted with the hen erythrocyte (Zentgraf et al, 1971).…”