Alignment of Amino Acid and DNA Sequences of Human Proline-rich Proteins

Abstract

Human proline-rich proteins (PRPs) constitute a complex family of salivary proteins that are encoded by a small number of genes. The primary gene product is cleaved by proteases, thereby giving rise to about 20 secreted proteins. To determine the genes for the secreted PRPs, therefore, it is necessary to obtain sequences of both the secreted proteins and the DNA encoding these proteins. We have sequenced most PRPs from one donor (D.K.) and aligned the protein sequences with available DNA sequences from unrelated individuals. Partial sequence data have now been obtained for an additional PRP from D.K. named II-1. This protein was purified from parotid saliva by gel filtration and ion-exchange chromatography. Peptides were obtained by cleavage with trypsin, clostripain, and N-bromosuccinimide, followed by column chromatography. The peptides were sequenced on a gas-phase protein sequenator. Overlapping peptide sequences were obtained for most of II-I and aligned with translated DNA sequences. The best fit was obtained with clones containing sequences for the allele PRB4M (Lyons et al., 1988). However, there was not complete identity of the protein amino acid sequence and the DNAderived sequences, indicating that II-I is not encoded by PRB4M. Other PRPs isolated from D.K. also fail to conform to any DNA structure so far reported. This shows the need to obtain amino acid sequences and corresponding DNA sequences from the same person to assign genes for the PRPs and to determine the location of the postribosomal cleavage points in the primary translation product.

Harnessing disorder: onychophorans use highly unstructured proteins, not silks, for prey capture

“…In particular, the onychophoran proteins share attributes with the mammalian proline-rich salivary proteins, which make up approximately 70 per cent of the proteins in human saliva (Kauffman et al 1993).…”

Facts and artifacts in proteomics of body fluids. What proteomics of saliva is telling us?

“…Moreover, at least three potential bPRPs of unknown structure, with a mass of 10434, 23462 and 29415 Da, are recurrently detected, and other peptides with masses compatible with this class are sporadically detected [11]. The connection between the most common genotypes and salivary phenotypes is waiting for definition [9].…”

“…Differently from aPRPs, which are contemporaneously present in saliva as entire and truncated isoforms, all the bPRP are detectable only as multiple peptide fragments deriving from bigger pro-proteins. The structure of several peptides has been established (IB-1, II-2, P-D or IB-5, P-E or IB-9, P-F or IB-8c, P-H or IB-4, IB-7, IB-8a or Con 1-variant [9,10]) but many pieces are missing for the definition of the entire mosaic. For instance, a peptide called P-J with a mass of 5945 Da is always detected in the LC-MS profile of saliva, but it is pending for a definitive characterization.…”

Interaction of Plant Polyphenols with Salivary Proteins

“…These include, according to the nomenclature of Kauffman and Keller (1979), IB1, IB4, IB5, IB6, IB7, IB8a, IB8b, IB8c, IB9, II-1, II-2, and GPRP. Of particular interest is the determination, in a single person, of both the amino acid sequences of the secreted proteins and nucleotide sequences of the genes encoding BPRPs and GPRPs, since it allows for the unequivocal assignment of the regions encoding the secreted proteins and the determination of the cleavage points in the proproteins (Kauffman et al ., 1982(Kauffman et al ., , 1986(Kauffman et al ., , 1991(Kauffman et al ., , 1993Stubbs et al ., 1998).…”