Induction by zinc of specific metallothionein isoforms in human monocytes.
A low-molecular-mass zinc-containing protein was isolated by gel permeation and anion-exchange chromatography of lysates of human monocytes induced with zinc acetate. Characterization by sodium dodecyl sulphate/polyacrylamide gel electrophoresis and amino acid sequencing identified the two major charge-separable fractions and an occasionally occurring third fraction as metallothionein-1, metallothionein-2 and metallothionein-0, respectively. Metallothionein-1 was shown to consist of a mixture of isoforms, confirmed as metallothionein-1e, metallothionein-1g and metallothionein-1l by comparison with cDNA sequences obtained by screening a human monocyte cDNA library. We can find no previous observation in the literature of metallothionein-1g at both the protein and RNA level in a non-tumour cell, and of metallothionein-0 in a non-fetal cell or tissue. Since isoform-specific polymerase-chain-reaction amplification showed the presence of metallothionein-0 mRNA in zinc-induced but not in untreated monocytes, these cells can be used as an in vitro system to investigate the expression of this previously considered fetal isoform.
Pauwels
M
M
Laboratorium voor Biochemie, Katholieke Universiteit Leuven, Belgium.
van Weyenbergh
J
J
Soumillion
A
A
Proost
P
P
De Ley
M
M
D000328:Adult; D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification; D018076:DNA, Complementary / Q000235:genetics; D005333:Fetus / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008668:Metallothionein / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D008969:Molecular Sequence Data; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015032:Zinc / Q000494:pharmacology*
D002352:Carrier Proteins; D018076:DNA, Complementary; D012333:RNA, Messenger; C017800:zinc-binding protein; D008668:Metallothionein; D015032:Zinc