ZINC-DEFICIENCY ALTERS THE PROTEIN-COMPOSITION OF THE MEMBRANE SKELETON BUT NOT THE EXTRACTABILITY OR OLIGOMERIC FORM OF SPECTRIN IN RAT ERYTHROCYTE-MEMBRANES

We examined the effect of dietary Zn deficiency on the composition and structure of the rat erythrocyte membrane skeleton. Weanling rats were given free access to egg white-based diets (< 1.0 mg Zn/kg) for 3 wk. Controls were fed diets (pair-fed or ad libitum) supplemented with 100 mg Zn/kg. Membrane skeleton proteins were extracted from isolated erythrocyte membranes in a low ionic strength buffer. Dietary Zn deficiency did not alter the content of spectrin, the major membrane skeleton protein, in the intact membranes or the percentage of spectrin extracted after 24 or 96 h. Zinc deficiency did not alter the oligomeric form of spectrin in the extracts that were analyzed in the presence or absence of EDTA. However, Zn deficiency resulted in a significant reduction in the relative content of protein R5 in the membrane skeleton extracts. The food restriction associated with dietary Zn deficiency was the major factor in the significant reduction in the relative content of RA (adducin) and R4 (protein 4.1) in the membrane skeleton extracts. Dietary Zn deficiency altered membrane skeleton protein composition but had no effect on the extractability or oligomeric form of spectrin.