JBC, Vol. 252, Issue 20, 7184-7191, Oct, 1977
Cystine requirement of continuous human lymphoid cell lines of normal and leukemic origin
J. K. Iglehart, R. M. York, A. P. Modest, H. Lazarus and D. M. Livingston
A number of continuous, human lymphoid cell lines from healthy and leukemic
donors have been studied. Those from healthy individuals were found to be
cystine prototrophs (cys+), while those from leukemic donors were observed
to be cystine auxotrophs (cys-). The former can grow in either cystine or
cystathionine-containing media. The latter grow only in cystine-containing
medium. The former contain readily measurable levels of cystathionase, the
last enzyme in the mammalian cysteine biosynthetic pathway, while the
latter contain much less of this activity. The apparent molecular weight,
overall charge, pH versus activity, Km, and [pyridoxal phosphate] versus
activity properties of the enzyme from both cell types were
indistinguishable. No soluble cystathionase inhibitor could be detected in
cys- cell lines. Thus, it is reasonable to hypothesize that those leukemic
cell lines studied synthesize less active cystathionase protein than their
cys+ counterparts and that this difference in enzyme production underlies
the differential growth properties in cystathionine-containing medium.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
