{'fraction_non_alphanumeric': 0.026515151515151516, 'fraction_numerical': 0.009848484848484848, 'mean_word_length': 4.897321428571429, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
CHARACTERISATION OF A TRANSPORT SYSTEM FOR CYSTINE IN LEUCOCYTES LYSOSOMAL MEMBRANES

Normal leucocyte lysosomal membranes are able to transport cystine by a saturable process exhibiting efflux (T) and Counter-transport (CT). Leucocyte lysosomes from cystinotic patients lack this carrier mediated transport and thus store cystine. In order to establish whether T and CT are mediated by the same site, the effect of proteolytic enzymes, ATP, different H+ concentrations and N-Ethyl-Maleimid (NEM) on these two activities were examined. T and CT were measured in lysosome rich granular fractions extracted from normal PMN leucocytes loaded with cystine. Protease inhibited CT of cystine by 80% but did not influence the rate of cystine efflux. Trypsin and Chymotrypsin had no effect on both T and CT. ATP (2mM) and NEM (10mM) inhibited CT by 35% and 50% respectively. Cystine efflux was enhanced by 50% by ATP and not effected by NEM. Lowering the proton gradient across the membrane by incubating the lysosomes in an acidic medium (PH 5.5) caused an inhibition of both T and CT of cystine.The observation that the two processes have different characteristics, yet both of them lack in cystinosis suggests that cystine T and CT occur at two different sites on a single protein carrier of the leucocyte lysosomal membrane.