TY - JOUR
T1 - Multiple isoforms of metallothionein are expressed in the porcine liver
AU - Huang, Min Chuan
AU - Pan, Peter K.
AU - Zheng, Zu Fan
AU - Chen, Nick C.
AU - Peng, Joyce Y.
AU - Huang, P. C.
N1 - Funding Information:
This study was supported in part by the National Science Council, Taiwan, ROC (NSC 84-231-B007-021 and 85-2113-M007-032).
PY - 1998/4/28
Y1 - 1998/4/28
N2 - Isogenes are highly homologous to each other and are often difficult to ascertain, as has been the case with metallothionein, a metal-binding protein rich in cysteines. Conventional separation of metallothionein isoforms relied on ion exchange chromatography of the proteins, or screening for the sequences from gene libraries. In this study, a combination of RT-PCR and partial protein sequencing is used in the identification of metallothionein isogenes expressed in porcine liver. By this approach, we have identified expressed coding sequences which constitute 10 new isogenes. Of the four known groups of metallothioneins (MT), phylogenetic analyses place these pig isogenes in the MT-1 group, except two which are identified as being closely related to MT-2, and none in groups 3 and 4. The isogenes are thus named pMT-1a to -1g, and pMT-2a and -2b. While each of the isogene sequences is unique, two isogenes, pMT-le1 and pMT-le2, share an identical amino acid sequence, differing only in specific codons. Two others, pMT-1b and pMT-1g, have a cysteine substituted by arginine, the first such sequence ever detected in MT. pMT-2a and pMT-2b are closely aligned with the MT-2 group of vertebrates, in spite of the absence of a characteristic acidic amino acid at position 10 or 11, common in other mammalian metallothioneins.
AB - Isogenes are highly homologous to each other and are often difficult to ascertain, as has been the case with metallothionein, a metal-binding protein rich in cysteines. Conventional separation of metallothionein isoforms relied on ion exchange chromatography of the proteins, or screening for the sequences from gene libraries. In this study, a combination of RT-PCR and partial protein sequencing is used in the identification of metallothionein isogenes expressed in porcine liver. By this approach, we have identified expressed coding sequences which constitute 10 new isogenes. Of the four known groups of metallothioneins (MT), phylogenetic analyses place these pig isogenes in the MT-1 group, except two which are identified as being closely related to MT-2, and none in groups 3 and 4. The isogenes are thus named pMT-1a to -1g, and pMT-2a and -2b. While each of the isogene sequences is unique, two isogenes, pMT-le1 and pMT-le2, share an identical amino acid sequence, differing only in specific codons. Two others, pMT-1b and pMT-1g, have a cysteine substituted by arginine, the first such sequence ever detected in MT. pMT-2a and pMT-2b are closely aligned with the MT-2 group of vertebrates, in spite of the absence of a characteristic acidic amino acid at position 10 or 11, common in other mammalian metallothioneins.
KW - Gene family
KW - HPLC
KW - RT-PCR
KW - cDNA
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U2 - 10.1016/S0378-1119(98)00067-5
DO - 10.1016/S0378-1119(98)00067-5
M3 - Article
C2 - 9573337
AN - SCOPUS:0032574672
SN - 0378-1119
VL - 211
SP - 49
EP - 55
JO - Gene
JF - Gene
IS - 1
ER -