A porcine homolog of the major secretory protein of human epididymis, HE1, specifically binds cholesterol.
A porcine homolog of the major secretory protein of human epididymis, HE1, was for the first time purified from the porcine cauda epididymal fluid. The HE1 homolog was secreted into the epididymal fluid as a 19-kDa glycoprotein, whose sugar moiety was gradually processed to form a 16-kDa protein during transit through the epididymis. The HE1 homolog mRNA was detected only in the caput and corpus epididymis among the porcine tissues examined. The purified HE1 homolog specifically bound cholesterol with high affinity (Kd=2. 3 microM). The binding stoichiometry was determined to be 0.94 mol/mol, suggesting that 1 mol of cholesterol binds to 1 mol of the protein. It was also found that the HE1 homolog is a major cholesterol-binding protein in the porcine epididymal fluid. The possibility that the HE1 homolog is involved in the regulation of the lipid composition of the sperm membranes during the maturation in epididymis is discussed.
Okamura
N
N
Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Ibaraki 305, Japan. naooka@igaku.md.tsukuba.ac.jp
Kiuchi
S
S
Tamba
M
M
Kashima
T
T
Hiramoto
S
S
Baba
T
T
Dacheux
F
F
Dacheux
J L
JL
Sugita
Y
Y
Jin
Y Z
YZ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001826:Body Fluids / Q000378:metabolism; D002352:Carrier Proteins / Q000302:isolation & purification; D002784:Cholesterol / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004822:Epididymis / Q000737:chemistry / Q000378:metabolism*; D015723:Gene Library; D006023:Glycoproteins / Q000302:isolation & purification / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010196:Pancreatic Elastase; D011506:Proteins; D012333:RNA, Messenger / Q000032:analysis; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013079:Sperm Maturation; D013094:Spermatozoa / Q000378:metabolism; D013552:Swine; D033921:Vesicular Transport Proteins
D002352:Carrier Proteins; D018076:DNA, Complementary; D006023:Glycoproteins; C104585:NPC2 protein, human; D011506:Proteins; D012333:RNA, Messenger; D033921:Vesicular Transport Proteins; D002784:Cholesterol; D010196:Pancreatic Elastase; C017130:cholesterol-binding protein