Primary structure of prostaglandin G/H synthase from sheep vesicular gland determined from the complementary DNA sequence.

Abstract

Prostaglandin G/H synthase (8,11,14-icosatrienoate,hydrogen-donor:oxygen oxidoreductase, EC 1.14.99.1) catalyzes the first step in the formation of prostaglandins and thromboxanes, the conversion of arachidonic acid to prostaglandin endoperoxides G and H. This enzyme is the site of action of nonsteroidal anti-inflammatory drugs. We have isolated a 2.7-kilobase complementary DNA (cDNA) encompassing the entire coding region of prostaglandin G/H synthase from sheep vesicular glands. This cDNA, cloned from a AgtlO libra7y prepared from poly(A)+ RNA of vesicular glands, hybridizes with a single 2.75-kilobase mRNA species. The cDNA clone was selected using oligonucleotide probes modeled from amino acid sequences of tryptic peptides prepared from the purified enzyme. The full-length cDNA encodes a protein of 600 amino acids, including a signal sequence of 24 amino acids. Identification of the cDNA as coding for prostaglandin G/H synthase is based on comparison of amino acid sequences of seven peptides comprising 103 amino acids with the amino acid sequence deduced from the nucleotide sequence of the cDNA. The molecular weight of the unglycosylated enzyme lacking the signal peptide is 65,621. The synthase is a glycoprotein, and there are three potential sites for N-glycosylation, two of them in the amino-terminal half of the molecule. The serine reported to be acetylated by aspirin is at position 530, near the carboxyl terminus. There is no significant similarity between the sequence of the synthase and that of any other protein in amino acid or nucleotide sequence libraries, and a heme binding site(s) is not apparent from the amino acid sequence. The availability of a full-length cDNA clone coding for prostaglandin G/H synthase should facilitate studies of the regulation of expression of this enzyme and the structural features important for catalysis and for interaction with anti-inflammatory drugs.

Glycosylation regulates turnover of cyclooxygenase‐2

“…COX is bifunctional, converting arachidonic acid (AA), an omega-6 fatty acid, to the precursor prostaglandin G 2 (PGG 2 ) and subsequently converting PGG 2 to the precursor PGH 2 via cyclooxygenase and peroxidase activities, respectively. Three isoforms of COX have been found -the constitutively expressed COX-1 [5][6][7]; COX-2, which can be inducible or constitutive, depending on the tissue [1,[8][9][10]; and the constitutively expressed COX-3, which is believed to be a splice variant of COX-1 [11]. Although COX-1 is considered the housekeeping enzyme expressed in nearly all tissues, COX-2 is generally perceived to be involved in pathological conditions, such as inflammation and cancer [1,12,13].…”

Induction of cyclo-oxygenase-2 mRNA by prostaglandin E2 in human prostatic carcinoma cells

“…COX-1 is a well-characterized, constitutively expressed enzyme originally purified from ovine and bovine vesicular glands and platelets (Smith, 1992;Smith et al, 1991). The cDNA clones of the 2.8-kb COX-l mRNA isolated from ovine (DeWitt and Smith, 1988), murine (DeWitt et al, 1990) and human tissues (Funk et al, 1991) encodes a protein of approximately 600 amino acids in length. The cDNA clones of the 4.4-kb COX-2 message have been isolated from various tissues of human and animal origin and also encode a protein of about 600 amino acids (Fletcher et al, 1992;Hla and Neilson, 1992).…”

Polymorphisms of the PTGDR and LTC4S influence responsiveness to leukotriene receptor antagonists in Korean children with asthma

“…[7][8][9] The effects of the PTGDR on asthma were shown with a mouse study; the asthmatic symptoms of PTGDR À/À mice were improved compare with wild-type mice. 8 In addition, PGD2 15 and LTC4 16,17 are both derived from arachidonic acid. However, the relationship between the PTGDR and responsiveness to a LTRA has not been investigated.…”

“…[15][16][17] However, the results of a recent study showed that PGD2 activated eosinophils and enhanced LTC4 synthesis in vivo. 18 Accumulating evidence suggests that the cysteinyl leukotrienes (cysLTs) are the primary mediators of exercise-induced bronchoconstriction (EIB), as demonstrated by the detection of cysLTs in the airways, 19 increased levels of urinary leukotriene E4 20 and increased levels of cysLTs in exhaled breath condensates, 21 and in induced sputum 22 from children with EIB.…”