Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Asymmetric forms of Torpedo acetylcholinesterase (AChE) are produced in COS cells by the simultaneous expression of collagenic subunits (Q) and catalytic T subunits (AChET). Truncated AChET delta subunits, from which most of the C-terminal peptide (TC) had been deleted by mutagenesis, did not associate with Q subunits. The TC peptide is therefore necessary for the association of the AChET and Q subunits. In order to determine the orientation of the Q subunit in the collagen-tailed forms, we have developed an antiserum against its non-collagenic C-terminal domain, expressed as a fusion protein in Escherichia coli. This antiserum, which recognized the Q subunit in Western blots, was found to react with intact asymmetric forms, but not with collagenase-treated forms, from which the distal part of the tail had been cleaved, suggesting that the N-terminal non-collogenic domain (QN) is responsible for the interaction with the AChET subunits. This was confirmed by creating a chimeric subunit (QN/HC), in which QN was linked to the C-terminal peptide of the H subunit of Torpedo AChE, which contains the glycophosphatidylinositol (GPI) cleavage/attachment signal: co-expression of AChET and QN/NC produced GPI-anchored tetramers, which were sensitive to PI-PLC and largely exposed to the external surface of the cells. We thus demonstrate that: (i) the HC peptide is sufficient to determine the addition of a glycolipid anchor and (ii) the QN domain is sufficient to bind a catalytic AChET tetramer by interacting with the TC peptide.
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PMID:Molecular architecture of acetylcholinesterase collagen-tailed forms; construction of a glycolipid-tailed tetramer. 138 Apr 51

Vasotocin receptors were investigated in glomeruli and nephron segments microdissected from collagenase-treated kidneys of Rana ridibunda, using [d(CH2)5Tyr(Me)2,Thr4,Orn8,125I-Tyr-NH2(9)]vasotocin (125I-OVTA) as a radioligand. Specific 125I-OVTA binding sites were found only in glomeruli and not in all tubule segments tested. Glomerular receptors exhibited the following stereospecificity for recognition of vasotocin analogues: Tyr-NH2(9)-LA-V1a > 125I-OVTA > arginine vasotocin (AVT) > or = [d(CH2)5Tyr-(Me)2]AVP > OVTA > or = [Phe2,Orn8]VT > oxytocin (OT) > or = [d(CH2)5-Sar7]AVP > desGly9[d(CH2)5Tyr(Et)2]VAVP > or = [d(CH2)5Tyr(Et)2]VAVP > AVP > [1-desamino-8-D-arginine]vasopressin (DDAVP) > [Thr4,Gly7]OT. In addition, vasotocin enhanced [3H]inositol phosphate production in sieved glomeruli labeled with myo-[3H]inositol; the rank order of structural vasotocin analogues for stimulation of phosphoinositidase C was [Phe2,Orn8]VT > AVT > OT > AVP > DDAVP, whereas [Thr4,Gly7]OT was almost inactive, and the rank order of antagonists for inhibition of hormone-induced enzyme activation was Tyr-NH2(9)-LA-V1a > [d(CH2)5Tyr(Me)2]AVP = OVTA > [d(CH2)5Sar7]AVP > [d(CH2)5Tyr(Et)2]VAVP > or = desGly9[d(CH2)5Tyr(Et)2]VAVP. Results indicate that the 125I-OVTA-labeled binding sites detected in frog glomeruli reveal the pharmacological properties of mammalian V1b-pituitary vasopressin receptors and might be physiological vasotocin receptors involved in phosphoinositidase C stimulation.
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PMID:Frog glomerular vasotocin receptors resemble mammalian V1b receptors. 797 46