Difference in distribution of membrane proteins between low- and high-density secretory granules in parotid acinar cells

Journal Article · Fri May 26 04:00:00 EDT 2006 · Biochemical and Biophysical Research Communications

DOI:https://doi.org/10.1016/j.bbrc.2006.03.130· OSTI ID:20798974

Fujita-Yoshigaki, Junko ^[1]; Katsumata, Osamu ^[1]; Matsuki, Miwako ^[2]; Yoshigaki, Tomoyoshi ^[1]; Furuyama, Shunsuke ^[1]; Sugiya, Hiroshi ^[1]

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1. Department of Physiology, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271-8587 (Japan)
2. Department of Pathology, Tokyo Dental College, Chiba 261-8502 (Japan)

Secretory granules (SGs) are considered to be generated as immature granules and to mature by condensation of their contents. In this study, SGs of parotid gland were separated into low-, medium-, and high-density granule fractions by Percoll-density gradient centrifugation, since it was proposed that the density corresponds to the degree of maturation. The observation with electron microscopy showed that granules in the three fractions were very similar. The average diameter of high-density granules was a little but significantly larger than that of low-density granules. Although the three fractions contained amylase, suggesting that they are all SGs, distribution of membrane proteins was markedly different. Syntaxin6 and VAMP4 were localized in the low-density granule fraction, while VAMP2 was concentrated in the high-density granule fraction. Immunoprecipitation with anti-syntaxin6 antibody caused coprecipitation of VAMP2 from the medium-density granule fraction without solubilization, but not from Triton X-100-solubilized fraction, while VAMP4 was coprecipitated from both fractions. Therefore, VAMP2 is present on the same granules, but is separated from syntaxin6 and VAMP4, which are expected to be removed from immature granules. These results suggest that the medium-density granules are intermediates from low- to high-density granules, and that the membrane components of SGs dynamically change by budding and fusion during maturation.

• OSTI ID: 20798974
• Journal Information: Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 1 Vol. 344; ISSN 0006-291X; ISSN BBRCA9
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
AMYLASE
ANTIBODIES
COPRECIPITATION
ELECTRON MICROSCOPY
GLANDS
MEMBRANE PROTEINS
MEMBRANES
TRITONS