| Autor: |
Hale, Calvin, Kleiboeker, Steven, Carlton, Carol, Rovetto, Michael, Jung, Chan, Kim, H. |
| Zdroj: |
Journal of Membrane Biology; 1988, Vol. 106 Issue 3, p211-218, 8p |
| Abstrakt: |
Cardiac sarcolemma (SL) vesicles were subjected to irradiation inactivation-target sizing analyses and gel permeation high performance liquid chromatography (HPLC) to ascertain the weight range of native Na−Ca exchange. Frozen SL vesicle preparations were irradiated by electron bombardment and assayed for Na−Ca exchange activity. When applied to classical target sizing theory, the results yielded a minimum molecular weight ( M) of approximately 226,000±20,000 sd ( n=6). SL vesicle proteins were solubilized in 6% sodium cholate in the presence of exogenous phospholipid and fractionated by size on a TSK 30XL HPLC column. Eluted proteins were mixed 1∶1 with mobile phase buffer containing 50mg/ml soybean phospholipid and reconstituted by detergent dilution. The resulting proteoliposomes were assayed for Na−Ca exchange activity. Na−Ca exchange activity eluted in early fractions containing larger proteins as revealed by SDS-PAGE. Recovery of total protein and Na−Ca exchange activity were 91±7 and 68±11%, respectively. In the peak fraction, Na−Ca exchange specific activity increased two-to threefold compared to reconstituted controls. Compared to the elution profile of protein standards under identical column conditions, sodium cholate solubilized exchange activity had a minimum M of 224,000 Da. SpecificCa-binding SL proteins with M of 234,000, 112,000, and 90,000 Da were detected by autoradiography of proteins transferred electrophoretically to nitrocellulose. These data suggest that native cardiac Na−Ca exchange is approximately 225,000 Da or larger. The exact identification and purification of cardiac Na−Ca exchange protein(s) remains incomplete. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
Full text from SpringerLink