Abstract
We determined protein disulphide-isomerase (PDI) and iodothyronine deiodinase (ID-I) activities in liver homogenates from rats subjected to selenium (Se) and/or iodine deficiencies and food restriction. Additionally, the effects of propylthiouracil (PTU) on the enzymes were studied in vivo and in vitro. Selenium deficiency markedly inhibited ID-I activity, but had no significant effects on PDI. Iodine deficiency resulted in a 1.6-fold stimulation in ID-I and a 1.2-fold stimulation in PDI activities. ID-I was much more sensitive than PDI to the inhibitory effects of PTU both in vitro and in vivo. By using a'3,3'5'-tri[I-125]iodothyronine affinity label, two major protein bands were identified when hepatic microsomal fractions from Se-sufficient rats were subjected to SDS/PAGE and autoradiography. These bands had molecular masses of 55 and 27.5 kDa, which are similar to those of PDI and ID-I respectively. Selenium deficiency resulted in the loss of the 27.5 kDa band, but did not affect the intensity of the 55 kDa band. These results are consistent with the changes in PDI and ID-I enzyme activities. Previous studies have shown that Se-75 may be incorporated in vivo into the 27.5 kDa protein band. This, taken together with our observation that Se is required for the expression of ID-I and the 27.5 kDa protein band, strongly suggests that ID-I is a selenoprotein.
| Original language | English |
|---|---|
| Pages (from-to) | 297-300 |
| Number of pages | 4 |
| Journal | Biochemical Journal |
| Volume | 274 |
| Publication status | Published - 15 Feb 1991 |
Keywords
- RAT-LIVER
- DISULFIDE ISOMERASE
- ENDOPLASMIC-RETICULUM
- NUCLEOTIDE-SEQUENCE
- BINDING-PROTEIN
- THYROXINE
- PURIFICATION
- INHIBITION
- SERUM
Cite this
THE EFFECTS OF SELENIUM DEFICIENCY ON HEPATIC TYPE-I IODOTHYRONINE DEIODINASE AND PROTEIN DISULFIDE-ISOMERASE ASSESSED BY ACTIVITY MEASUREMENTS AND AFFINITY LABELING. / Arthur, John; Nicol, Fergus; GRANT, E ; BECKETT, G J .
In: Biochemical Journal, Vol. 274, 15.02.1991, p. 297-300.Research output: Contribution to journal › Article
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TY - JOUR
T1 - THE EFFECTS OF SELENIUM DEFICIENCY ON HEPATIC TYPE-I IODOTHYRONINE DEIODINASE AND PROTEIN DISULFIDE-ISOMERASE ASSESSED BY ACTIVITY MEASUREMENTS AND AFFINITY LABELING
AU - Arthur, John
AU - Nicol, Fergus
AU - GRANT, E
AU - BECKETT, G J
PY - 1991/2/15
Y1 - 1991/2/15
N2 - We determined protein disulphide-isomerase (PDI) and iodothyronine deiodinase (ID-I) activities in liver homogenates from rats subjected to selenium (Se) and/or iodine deficiencies and food restriction. Additionally, the effects of propylthiouracil (PTU) on the enzymes were studied in vivo and in vitro. Selenium deficiency markedly inhibited ID-I activity, but had no significant effects on PDI. Iodine deficiency resulted in a 1.6-fold stimulation in ID-I and a 1.2-fold stimulation in PDI activities. ID-I was much more sensitive than PDI to the inhibitory effects of PTU both in vitro and in vivo. By using a'3,3'5'-tri[I-125]iodothyronine affinity label, two major protein bands were identified when hepatic microsomal fractions from Se-sufficient rats were subjected to SDS/PAGE and autoradiography. These bands had molecular masses of 55 and 27.5 kDa, which are similar to those of PDI and ID-I respectively. Selenium deficiency resulted in the loss of the 27.5 kDa band, but did not affect the intensity of the 55 kDa band. These results are consistent with the changes in PDI and ID-I enzyme activities. Previous studies have shown that Se-75 may be incorporated in vivo into the 27.5 kDa protein band. This, taken together with our observation that Se is required for the expression of ID-I and the 27.5 kDa protein band, strongly suggests that ID-I is a selenoprotein.
AB - We determined protein disulphide-isomerase (PDI) and iodothyronine deiodinase (ID-I) activities in liver homogenates from rats subjected to selenium (Se) and/or iodine deficiencies and food restriction. Additionally, the effects of propylthiouracil (PTU) on the enzymes were studied in vivo and in vitro. Selenium deficiency markedly inhibited ID-I activity, but had no significant effects on PDI. Iodine deficiency resulted in a 1.6-fold stimulation in ID-I and a 1.2-fold stimulation in PDI activities. ID-I was much more sensitive than PDI to the inhibitory effects of PTU both in vitro and in vivo. By using a'3,3'5'-tri[I-125]iodothyronine affinity label, two major protein bands were identified when hepatic microsomal fractions from Se-sufficient rats were subjected to SDS/PAGE and autoradiography. These bands had molecular masses of 55 and 27.5 kDa, which are similar to those of PDI and ID-I respectively. Selenium deficiency resulted in the loss of the 27.5 kDa band, but did not affect the intensity of the 55 kDa band. These results are consistent with the changes in PDI and ID-I enzyme activities. Previous studies have shown that Se-75 may be incorporated in vivo into the 27.5 kDa protein band. This, taken together with our observation that Se is required for the expression of ID-I and the 27.5 kDa protein band, strongly suggests that ID-I is a selenoprotein.
KW - RAT-LIVER
KW - DISULFIDE ISOMERASE
KW - ENDOPLASMIC-RETICULUM
KW - NUCLEOTIDE-SEQUENCE
KW - BINDING-PROTEIN
KW - THYROXINE
KW - PURIFICATION
KW - INHIBITION
KW - SERUM
M3 - Article
VL - 274
SP - 297
EP - 300
JO - Biochemical Journal
JF - Biochemical Journal
SN - 0264-6021
ER -