Evidence that a calmodulin-like calcium-binding domain of the FSH beta-subunit is involved in FSH-induced calcium uptake by Sertoli cells.
We have previously shown that a synthetic peptide amide corresponding to residues 1-15 of the human FSH beta-subunit (hFSH-beta-(1-15)) possesses structural characteristics and calcium-binding properties similar to the calcium-binding loops of calmodulin (CaM). The calcium-binding property of hFSH-beta-(1-15) correlated well with its ability to stimulate uptake of calcium (as 45Ca2+) by cultured rat Sertoli cells and proteoliposomes enriched with bovine calf testis FSH receptors. A sequence found in the calcium-binding loops of CaM and a number of other calcium-binding proteins can be represented by the motif +-+-+-+-+--+, where + represents a calcium-binding residue and - represents a non-binding residue. A sequence containing a similar motif appears in hFSH-beta-(1-15) between residues 4 and 15: +-++-+---+-+. Using a synthetic peptide strategy, we undertook to determine whether the first three residues of hFSH-beta-(1-15) were required to induce uptake of calcium by cultured rat Sertoli cells and FSH receptor-enriched proteoliposomes, and to assess whether rearrangement of the putative calcium-binding ligands (+) of hFSH-beta-(1-15) to correspond to their linear sequence in CaM would enhance the ability of hFSH-beta-(1-15) to induce calcium uptake in these two model systems.(ABSTRACT TRUNCATED AT 250 WORDS)
Grasso
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Department of Biochemistry and Molecular Biology, Albany Medical College, New York 12208.
Reichert
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D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D005640:Follicle Stimulating Hormone / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects; D008297:Male; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D011510:Proteolipids; D051381:Rats; D012708:Sertoli Cells / Q000187:drug effects* / Q000378:metabolism*; D013329:Structure-Activity Relationship
D002147:Calmodulin; D010446:Peptide Fragments; D011510:Proteolipids; C020485:proteoliposomes; D005640:Follicle Stimulating Hormone; D002118:Calcium