The amino acid sequence of AQN-3, a carbohydrate-binding protein isolated from boar sperm. Location of disulphide bridges.
Gamete recognition and adhesion are essential steps in fertilization. Among others, carbohydrate-binding proteins on the sperm surface have been recognized to play a central role in the initial interaction of the male gamete with components of the zona pellucida of the homologous investing oocyte. We have isolated several members of a carbohydrate- and zona pellucida-binding protein family from ejaculated sperm. Here we report the biological origin and structural characterization of AQN-3, a component of this carbohydrate-binding family. The molecular weight of purified AQN-3 was determined by plasma desorption mass spectrometry. The protein was chemically and enzymatically degraded, the proteolytic fragments isolated and characterized by N-terminal sequencing and fast atom bombardment mass spectrometry. In this manner we established the complete amino acid sequence of AQN-3 and the location of its two disulphide bonds. No analogous protein sequence could be found in the MIPS protein sequence data bank, indicating that AQN-3 may belong to a novel mammalian carbohydrate-binding protein family.
Department of Dermatology, University of München, Germany.
L
L
Sanz
J J
JJ
Calvete
K
K
Mann
W
W
Schäfer
E R
ER
Schmid
E
E
Töpfer-Petersen
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011956:Receptors, Cell Surface; D029589:Seminal Plasma Proteins; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013094:Spermatozoa / Q000737:chemistry*; D013552:Swine
D002352:Carrier Proteins; D011956:Receptors, Cell Surface; D029589:Seminal Plasma Proteins; C055213:saccharide-binding proteins; C425042:spermadhesin