Molecular size of a sodium-dependent amino acid transporter in Ehrlich ascites cell plasma membranes estimated by radiation inactivation

Biochemistry ◽  
1991 ◽  
Vol 30 (15) ◽  
pp. 3704-3709 ◽  
Author(s):  
John I. McCormick ◽  
Marc Jette ◽  
Michel Potier ◽  
Richard Beliveau ◽  
Rose M. Johnstone
Keyword(s):  
Amino Acid ◽  
Plasma Membranes ◽  
Molecular Size ◽  
Amino Acid Transporter ◽  
Ascites Cell ◽  
Radiation Inactivation ◽  
Cell Plasma ◽  
Ehrlich Ascites ◽  
Sodium Dependent ◽  
Ehrlich Ascites Cell

scholarly journals Identification of the integrin α3β1 as a component of a partially purified A-system amino acid transporter from Ehrlich cell plasma membranes

1995 ◽  
Vol 311 (3) ◽  
pp. 743-751 ◽  
Author(s):  
J I McCormick ◽  
R M Johnstone
Keyword(s):  
Amino Acid ◽  
Amino Acid Transport ◽  
Plasma Membranes ◽  
Amino Acid Transporter ◽  
Acid Transport ◽  
Transport Activity ◽  
Western Blots ◽  
Ehrlich Cell ◽  
Cell Plasma ◽  
Beta 1 Integrin

We have previously reported [McCormick and Johnstone (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 7877-7881] the partial purification of the Na(+)-dependent A-system amino acid transporter from Ehrlich cell plasma membranes and have suggested that a 120-130 kDa peptide, a major component of the purified fraction [octyl glucoside (OG) extract], is involved in Na(+)-dependent amino acid transport. In the present study, N-terminal sequence analysis of the 120-130 kDa peptide revealed a sequence similar to that of the alpha 3 subunit of the integrin alpha 3 beta 1. The presence of alpha 3 beta 1 was confirmed by Western blots of the OG extract probed with anti-alpha 3 or -beta 1 antibodies. Western blots also showed that an antibody originally raised against the 120-130 kDa peptide crossreacts with both the alpha 3 and beta 1 integrin subunits. Co-purification of alpha 3 beta 1 and Na(+)-dependent transport activity suggested that the two activities might be associated. Evidence that alpha 3 plays a role in transport is shown by the fact that an antibody against human alpha 3, but not beta 1, removed transport activity (approximately 25% loss) from cholate-solubilized Ehrlich membranes. Further purification of OG extracts using concanavalin A and wheat-germ lectin columns resulted in the separation of transport activity from the bulk (but not all) of alpha 3 beta 1 integrin without loss of the transport activity. These results indicate that the integrin itself is not essential for amino acid transport. Reconstitution of a purified alpha 3 beta 1-depleted protein fraction showed high levels of Na(+)-dependent, alpha-methylaminoisobutyric-acid-inhibitable amino acid transport in proteoliposomes, whereas reconstituted integrin alone showed little transport activity. However, in the integrin-depleted fractions, high amino acid uptake occurred in K+ which compromised the accurate measurement of the Na(+)-dependent component of uptake. The data suggest that alpha 3 may be associated with the A-system transporter and may modulate the activity of this carrier. Moreover, transfection of K562 and RD cells with human alpha 3 and alpha 2 cDNA showed that the former but not the latter increased A-system transport, thus providing more direct evidence that alpha 3 may modulate A-system transport activity.

Role of specific acidic lipids on the reconstitution of sodium-dependent amino acid transport in proteoliposomes derived from Ehrlich cell plasma membranes

Biochemistry ◽  
1990 ◽  
Vol 29 (19) ◽  
pp. 4575-4581 ◽  
Author(s):  
Guorong Lin ◽  
John I. McCormick ◽  
Sirano Dhe-Paganon ◽  
John R. Silvius ◽  
Rose M. Johnstone
Keyword(s):  
Amino Acid ◽  
Amino Acid Transport ◽  
Plasma Membranes ◽  
Acid Transport ◽  
Ehrlich Cell ◽  
Cell Plasma ◽  
Sodium Dependent ◽  
Acidic Lipids
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