Basic proline-rich proteins of murine parotid glands. Induction of mRNA by isoprenaline and post-secretion processing.
Five major basic polypeptides with characteristics typical of proline-rich proteins, accumulated in parotid glands after long term isoprenaline treatment of Balb C mice. They were studied by two-dimensional gel electrophoresis and designated B1 degree, B2' degrees, B2 degrees, B3 degrees and B4 degrees on the basis of pI-dependent mobility. They were not observed in the glands of normal mice and were precipitated when glands were homogenized in 10% trichloroacetic acid unlike the three isoprenaline-induced proline-rich proteins of murine parotid glands reported previously. Isoprenaline induced six proline-rich in vitro translation products which were absent normally. Four of these species had pI-dependent mobilities almost identical to B1 degree, B2 degrees, B3 degrees and B4 degrees, indicating not only precursor/product relationships, but also that isoprenaline induced the accumulation of the proteins by regulating the mRNA. Identical salivary counterparts of the basic glandular proline-rich proteins were not detected whereas a series of smaller and more basic isoprenaline-induced polypeptides were observed in saliva (major speices B1s-B4s). The glandular proline-rich proteins were secreted from parotid tissue in vitro and the data indicate that proline-rich proteins are synthesised as precursors and processed into salivary form in the parotid glands after secretion. The relationships between the B-type in vitro translation products, parotid gland precursors and salivary proteins were also confirmed immunologically.
Bannister
A J
AJ
Department of Biochemistry, University of Sheffield, England.
Divecha
N
N
Ashmore
M
M
McDonald
C J
CJ
D000818:Animals; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008970:Molecular Weight; D010306:Parotid Gland / Q000187:drug effects / Q000378:metabolism*; D010452:Peptide Biosynthesis; D010455:Peptides / Q000235:genetics* / Q000302:isolation & purification; D010750:Phosphoproteins / Q000235:genetics*; D055232:Proline-Rich Protein Domains; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics*; D012016:Reference Values; D012463:Saliva / Q000032:analysis; D014158:Transcription, Genetic / Q000187:drug effects*
D010455:Peptides; D010750:Phosphoproteins; D012333:RNA, Messenger; D007545:Isoproterenol