TY - JOUR
T1 - Kinetic and immunologic evidence for the absence of glucose-6-phosphatase in early human chorionic villi and term placenta
AU - Barash, Varda
AU - Riskin, Aryeh
AU - Shafrir, Eleazar
AU - Waddell, Ian D.
AU - Burchell, Ann
N1 - Funding Information:
We thank ,~drs. S. Yosha and Mrs. B. Morag for their exceller:~ ',echnle~l assistance. The work carried out in Jerusalem was supported in part by the Joint Hebrew University - Hadassah Research Fund. A.B. is a Lister Institute Research Fellow. The work carried out in Dundee was funded by a grant from the Scottish Home and Health Department to A.B.
PY - 1991/1/23
Y1 - 1991/1/23
N2 - The existence of the enzyme glucose-6-phosphatase (G6Pase) in early and term human placenta was investigated by comparing the characteristics of placental microsomal glucose 6-phosphate (G6 P) hydrolytic activity and liver G6Pase. Placental microsomes exhibited similar apparent Km values for G6 P and β-glycerophosphate in intact and deoxycholate-treated microsomes, heat stability at acidic pH, low latency of mannose 6-phosphate hydrolysis, very low activity of pyrophosphate:glucose phosphotransferase, and undetectable [U-14C]G6 P transport into the placental microsomes, all of which indicated that specific G6Pase activity does not exist in placenta. Immunological evidence of the absence of both 36.5 kDa and T2 proteins, which represent the G6Pase catalytic protein and the phosphate / pyrophosphate transporter protein, respectively, confirmed that early and term human placenta are devoid of the multicomponent G6Pase enzyme.
AB - The existence of the enzyme glucose-6-phosphatase (G6Pase) in early and term human placenta was investigated by comparing the characteristics of placental microsomal glucose 6-phosphate (G6 P) hydrolytic activity and liver G6Pase. Placental microsomes exhibited similar apparent Km values for G6 P and β-glycerophosphate in intact and deoxycholate-treated microsomes, heat stability at acidic pH, low latency of mannose 6-phosphate hydrolysis, very low activity of pyrophosphate:glucose phosphotransferase, and undetectable [U-14C]G6 P transport into the placental microsomes, all of which indicated that specific G6Pase activity does not exist in placenta. Immunological evidence of the absence of both 36.5 kDa and T2 proteins, which represent the G6Pase catalytic protein and the phosphate / pyrophosphate transporter protein, respectively, confirmed that early and term human placenta are devoid of the multicomponent G6Pase enzyme.
KW - (Human placenta)
KW - Chorionic villi
KW - Glucose-6-phosphatase
KW - Microsome
UR - http://www.scopus.com/inward/record.url?scp=0026034151&partnerID=8YFLogxK
U2 - 10.1016/0304-4165(91)90197-O
DO - 10.1016/0304-4165(91)90197-O
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C2 - 1846754
AN - SCOPUS:0026034151
SN - 0304-4165
VL - 1073
SP - 161
EP - 167
JO - Biochimica et Biophysica Acta - General Subjects
JF - Biochimica et Biophysica Acta - General Subjects
IS - 1
ER -