The PBII gene of the human salivary proline-rich protein P-B produces another protein, Q504X8, with an opiorphin homolog, QRGPR.

Objectives: The NCBI gene database and human-transcriptome database for alternative splicing were used to determine the expression of mRNAs for P-B (SMR3B) and variant form of P-B. The translational product from the former mRNA was identified as the protein named P-B, whereas that from the latter has not yet been elucidated. In the present study, we investigated the expression of P-B and its variant form at the protein level.

Identification of cysteine proteases and screening of cysteine protease inhibitors in biological samples by a two-dimensional gel system of zymography and reverse zymography.

We have developed a two-dimensional (2D-) gel system of zymography and reverse zymography for the detection and characterization of proteases and protease inhibitors. Isoelectric focusing (IEF) agarose gels with pH gradients were employed for separation in the first-dimension and sodium dodecyl sulfate (SDS)-polyacrylamide gel copolymerized with gelatin used for the second dimension. Proteases and protease inhibitors separated by IEF gel were applied on the second gel without trichloroacetic acid (TCA) fixation.

Evidence for inclusion of a segment of Escherichia coli genomic DNA in bovine tooth germ mRNA encoding salivary proline-rich protein P-B.

In the course of cloning of bovine cDNA for proline-rich protein (PRP) P-B from bovine tooth germ cDNA, we found that one clone with 662 bp contained a 5'-terminal 393 bp (1-393 bp) sequence essentially identical to that of human P-B cDNA (154-546 in D29833) and bovine P-B cDNA (1-356 bp in AB192573) and a sequence of 233 bp (394-626 bp) highly homologous to the segment of E. coli K12 genomic DNA (365511-365744 in NC000913). Although the latter sequence is contained in the vector pT7Blue, which we used, our results show that this chimeric structure in bovine tooth germ P-B cDNA is not an artifact formed during the cloning process, but intrinsic to the bovine genome since the chimeric structure was detected in bovine tooth germ and bovine genomic DNA.

A novel cysteine protease inhibitor with lectin activity from the epidermis of the Japanese eel Anguilla japonica.

A novel cysteine protease inhibitor (Eel-CPI-1) was isolated from the epidermis of the eel. Eel-CPI-1 was shown to bind strongly to both lactose- and carboxymethylated papain-affinity gels. Its molecular mass under reducing condition was determined to be 18 kDa by SDS-polyacrylamide gel electrophoresis but approximately 30.

Tissue distribution and nucleotide sequence of bovine mRNA for salivary proline-rich protein P-B.

The tissue distribution of P-B was investigated to obtain information on the physiological significance of this proline-rich protein. To design primers and probes for a tissue distribution analysis, a polymerase chain reaction (PCR)-based cloning of bovine P-B cDNA was performed using tooth germ and the nucleotide sequence was determined. The cloned bovine P-B cDNA was composed of 356 bp and included the region corresponding to the mature P-B protein and part of the 3' non-coding sequence.