Why is the actual band size on a western blot different from the predicted size of the protein?
Western blotting is based on the separation of proteins by their size on a gel. However, migration of proteins through the gel matrix is also affected by other factors, which may cause the observed band size to be different from the predicted size.
Common causes are:
-Post-translational modification; for example phosphorylation and glycosylation increase the size of the protein
-Post-translation cleavage; many proteins are synthesized as precursor proteins, and then cleaved to give the active form
-Multimers, for example dimerization of a protein. This is usually prevented under reducing conditions, although strong interactions can result in the appearance of higher bands
-Splice variants; alternative splicing may result in different sized proteins being produced from the same gene
-Relative charge; the composition of amino acids (charged vs. non-charged)
What are the standard lysis buffers used with mammalian cells for detection of protein expression by immunoprecipitation (IP) or Western blot analysis?
The most commonly used buffer is RIPA Buffer with SDS. We offer RIPA Buffer (Cat. Nos. 89900 and 89901). We also offer the Pierce IP Lysis buffer (Cat. Nos. 87787 and 87788) as well as M-PER (Cat. Nos. 78501, 78503, and 78505).
What conditions do you recommend for overnight Western transfer?
Doing an overnight Westerm transfer is not the preferred method but can be done. The power should be lowered and the buffer should be chilled or the unit should be placed in the cold room to prevent overheating. You may try an overnight transfer at 5-15 V and adjust accordingly. You may also wish to put a second membrane behind the first in order to bind any proteins that transfer through the first membrane. You can use both membranes for staining, immunoblotting, or analysis.
Can I purchase the Secondary Antibody solutions from the WesternBreeze Chemiluminescent Detection kits as standalone products?
The goat anti-mouse and goat anti-rabbit secondary antibody solutions AP-conjugated are available as standalone products (Cat. Nos. WP20006 and WP20007), but the rabbit anti-goat secondary antibody solution AP-conjugated is not available as a standalone product.
Hypomorphic apolipoprotein E mice: a new model of conditional gene repair to examine apolipoprotein E-mediated metabolism.
Authors: Raffai Robert L; Weisgraber Karl H;
Journal:J Biol Chem
PubMed ID:11792702
'In creating an allelic variant of mouse Apoe designed to resemble human apolipoprotein E4 (apoE4), we generated hypomorphic apoE (hypoE) mice that express only approximately 5% of normal apoE mRNA levels in all tissues. Insertion of a neo cassette flanked by loxP sites in the third intron of Apoe reduced ... More
An iron-regulated ferric reductase associated with the absorption of dietary iron.
Authors:McKie AT, Barrow D, Latunde-Dada GO, Rolfs A, Sager G, Mudaly E, Mudaly M, Richardson C, Barlow D, Bomford A, Peters TJ, Raja KB, Shirali S, Hediger MA, Farzaneh F, Simpson RJ.
Journal:Science
PubMed ID:11230685
The ability of intestinal mucosa to absorb dietary ferric iron is attributed to the presence of a brush-border membrane reductase activity that displays adaptive responses to iron status. We have isolated a complementary DNA, Dcytb (for duodenal cytochrome b), which encoded a putative plasma membrane di-heme protein in mouse duodenal ... More