A study of properties and abundance of the components of liver carnitine palmitoyltransferases in mitochondrial inner and outer membranes. Effects of hypothyroidism, fasting and a ketotic diabetic state
| Autor: | E D Saggerson, Iraj Ghadiminejad |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 1991 |
| Předmět: |
medicine.medical_specialty
endocrine system endocrine system diseases Blotting Western Mitochondria Liver Mitochondrion In Vitro Techniques Biochemistry Diabetes Mellitus Experimental chemistry.chemical_compound Hypothyroidism Internal medicine Diabetes mellitus medicine Animals Carnitine Molecular Biology IC50 Carnitine O-Palmitoyltransferase Rats Inbred Strains Cell Biology Fasting Intracellular Membranes Ketosis medicine.disease Rats Malonyl Coenzyme A Membrane Endocrinology Malonyl-CoA Membrane protein chemistry Specific activity Carrier Proteins hormones hormone substitutes and hormone antagonists medicine.drug Research Article |
| Popis: | 1. Liver mitochondrial outer and inner membranes were isolated from normal, 48 h-fasted, streptozotocin-diabetic and hypothyroid rats. 2. Relative to membrane protein, fasting and diabetes substantially increased the activity of carnitine palmitoyltransferase (CPT) in outer membranes. Inner-membrane CPT specific activity was only slightly altered, being increased in diabetes and decreased in hypothyroidism. Abundance of an inner-membrane Mr-68,000 polypeptide that cross-reacted with an anti-CPT serum was significantly increased in diabetes and hypothyroidism. Relative to inner-membrane CPT activity, this cross-reactivity was increased by 37% in diabetes and by 400% in hypothyroidism, suggesting modification of the intrinsic activity of the CPT in these states. 3. CPT in outer membranes was inhibitable by malonyl-CoA, whereas inner-membrane CPT was insensitive to malonyl-CoA. Fasting and diabetes increased the IC50 (concentration of malonyl-CoA causing 50% inhibition) for outer-membrane CPT, whereas the IC50 was decreased in hypothyroidism. 4. Binding of [14C]malonyl-CoA was observed with both outer and inner membranes and was fitted to two-site models in each case. Fasting, diabetes and hypothyroidism changed the KD for binding at the higher-affinity site in outer membranes in a manner that correlated closely with changes in IC50 for inhibition of outer-membrane CPT by malonyl-CoA. Fasting and diabetes increased the abundance of this outer-membrane high-affinity malonyl-CoA-binding site, whereas hypothyroidism decreased its abundance. |
| Databáze: | OpenAIRE |
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