High performance liquid chromatography maps of tryptic and chymotryptic peptides from the W and L forms of rat phenylalanine hydroxylase differed by one peptide. Sequencing of the variant tryptic peptides showed a substitution of threonine in the W form by isoleucine in the L form and this same difference was confirmed in the chymotryptic peptides. This allelic substitution would result from a nucleotide change of ACA to ATA at amino acid position 371 of the full phenylalanine hydroxylase sequence. Altered sodium dodecyl sulphate binding is postulated to explain the change in mobility of the proteins observed on sodium dodecyl sulphate/polyacrylamide gels.

A child with the type VII form of the Ehlers-Danlos syndrome was shown to have a structural defect in the amino terminus of the pro-alpha 1(I) chain of type I procollagen. Normal and mutant amino-terminal cyanogen bromide peptides (pN-alpha 1(I) CB0,1 peptides) were purified from the medium of the patient's cultured fibroblasts. Amino acid sequencing of tryptic peptides derived from the mutant pN-alpha 1(I) CB0,1 peptide showed that an expected sequence of 24 amino acids (positions 136-159 of the normal pN-alpha 1(I) CB0,1 peptide) was deleted. The segment deleted from the mutant pro-alpha 1(I) chain contains the small globular region of the NH2-propeptide, the procollagen N-proteinase cleavage site, the NH2-telopeptide, and first triplet of the helix of the alpha I(I) collagen chain (Chu, M.-L., de Wet, W., Bernard, M., Ding, J.F., Morabito, M., Myers, J., Williams, C., and Ramirez, F. (1984) Nature 310, 337-340). Loss of the procollagen N-proteinase cleavage site from the mutant pro-alpha 1(I) chain accounted for the persistence of its NH2-propeptide despite normal production of the N-proteinase by cultured mutant fibroblasts. Collagen production by mutant fibroblasts was doubled possibly due to reduced feedback inhibition by the NH2-propeptides. The child appeared to be heterozygous for the peptide deletion and, as the parents did not show any evidence of the deletion, it is likely that the child had a new mutation of one allele of the pro-alpha 1(I) gene. The deleted peptide corresponds precisely to the sequence coded by exon 46 of the normal pro-alpha 1(I) gene (Chu, M.-L., de Wet, W., Bernard, M., Ding, J.F., Morabito, M., Myers, J., Williams, C., and Ramirez, F. (1984) Nature 310, 337-340).

The murine Fc receptor for IgG (Fc gamma R) was purified to homogeneity by immunoaffinity chromatography from detergent lysates of the macrophage cell line J774. Microsequencing of intact protein yielded a single amino-terminal sequence, which was confirmed and extended to 20 residues by the isolation of an overlapping peptide. The isolation of additional proteolytic fragments obtained by using Staphylococcus aureus V8 protease, cyanogen bromide, and lysine C proteinase, facilitated sequence analysis of a total of 119 amino acid residues. Codon usage charts were used to construct oligonucleotide probes based on the amino acid sequences of three nonoverlapping peptides. These probes were used to screen a cDNA library derived from the WEHI-3B myelomonocytic cell line, and a single cDNA clone (pFc24) to which all three probes hybridized was isolated. This clone, containing a 1.02-kilobase cDNA insert, has been characterized by restriction mapping and partial DNA sequencing, and it has been shown to encode the Fc gamma R. The sequence at the 5' end of the clone contained the coding information for the amino-terminal sequence of the Fc gamma R as well as a putative 13-amino acid signal sequence. The 3' end of the clone encoded a peptide identified in purified receptor preparations. Thus, the presence of coding information at the 5' and 3' ends of this clone suggests that full-length Fc receptor cDNA spans greater than 1 kilobase.