Binding of chemotactic peptide to the outer surface and to whole human spermatozoa with different affinity states.
Binding of N-formyl-methionyl-L-leucyl-[3H]phenylalanine (fML[3H]Ph) to human ejaculated spermatozoa and to its isolated plasma membrane was studied. Our data confirm the presence of specific receptors for f-MLPh in the human spermatozoa and suggest that whole spermatozoa receptors exist in two affinity states, one high-affinity, low-capacity specific receptor (Kd = 12.3 +/- 0.5 nM, n = 22,285 +/- 65,008 binding sites per sperm cell) and a second one (Kd = 700 +/- 47 nM) that is not saturable, indicating a low-affinity, high-capacity nonspecific site. In contrast, sperm membrane showed only one class of binding site (Kd = 6.4 +/- 0.12 nM), which was statistically different from that of the high-affinity binding site of intact spermatozoa. To explain this difference we discuss the possibility that first, the two binding affinities represent two interconvertible states of a single receptor population, which, depending on the metabolic activity of spermatozoa, may change its physicochemical properties; or second, they reflect two different processes, binding and/or transport into the spermatozoa.
Ballesteros
L M
LM
Laboratorio de Biologia Molecular, Instituto Mexicano del Seguro Social, Mexico, D.F.
Delgado
N M
NM
Rosado
A
A
Correa
C
C
Hernandez-Perez
O
O
D002462:Cell Membrane / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000378:metabolism*; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000378:metabolism*; D013094:Spermatozoa / Q000378:metabolism*
D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D009240:N-Formylmethionine Leucyl-Phenylalanine