Reevaluation of the amino acid sequence of porcine follitropin

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Abstract
We have reevaluated the sequence of porcine follicle-stimulating hormone (pFSH) with more recent protein-sequencing methodology. This has led to revision of the earlier proposed sequence. As with almost all reported gonadotropin α-subunits, NH2-terminal heterogeneity was found in the porcine FSH α-subunit (FSHα), starting with residue Phe (1), Asp (3), Gly (4), or Thr (7). In the β-subunit, there were found to be at least two molecular species, starting with residue Asn (1) (minor 20%) or Cys (3) (major 80%) as NH2-terminal and ending at residue Glu (108) as COOH-terminal. The net effect of the present revisions is to increase the homology of pFSHβ with other reported follitropin sequences. Apparent differences in the half-cystine placements in a previous proposal for pFSHβ compared with other species of FSH are no longer tenable. The half-cystine placements thus remain a constant structural feature throughout the gonadotropin hormones (choriogonadotropin, follitropin, and lutropin).