The granin family - Its role in sorting and secretory granule formation

H Ozawa
K Takata

Two types of secretory pathways are present in mammalian cells: constitutive secretion and regulated secretion (1). In the constitutive secretory pathway
 which is found in all types of cells
 secretory products are packed in small vesicles. Most of the proteoglycans and glycoproteins of the extracellular matrix are secreted in this way. The regulated secretory pathway
 found in the more differentiated secretory cells
 is mediated by specialized secretory granules. Hormones and neuropeptides are secreted in this way. Both the constitutive and regulated secretory pathways emanate from the trans-Golgi network (TGN).Recent studies have indicated that the granin family (secretogranins/chromogranins) plays an important role in the sorting and aggregation of secretory products in the trans-Golgi network (TGN)
 and in the subsequent formation of secretory granules. The granin family is thought to be one of the mediators of the regulated secretory pathway (2-6). This family is widely expressed in endocrine (7-9) and neuronal cells (10-12)
 where they are stored in secretory granules together with various peptide hormones and neuropeptides. Three acidic sulfated proteins
 chromogranin A (Cg A)
 secretogranin I (Sg I; also called chromogranin B; Cg B)
 and secretogranin II (Sg II) are well known as the major proteins in the family. Recently
 three acidic secretory proteins
 1B1075 gene product (13)
 HISL-19 antigen (14) and 7B2 (15)
 have been thought to be members of the granin family
 accordingly termed as Sg III
 Sg IV and Sg V
 respectively. However
 it still remains open to discussion whether 1B1075 gene product
 the HISL-19 antigen and 7B2 are true members of the granin family.In this review
 the possible roles of granin family
 especially Cg A
 Sg I (Cg B) and Sg II in the regulated secretory pathway are discussed
 focusing on the sorting
 aggregation of proteins in the TGN
 and subsequent secretory granule formation.

CELL STRUCTURE AND FUNCTION

JAPAN SOC CELL BIOLOGY

20

6

10.1247/csf.20.415

http://ci.nii.ac.jp/naid/10001913344
https://doi.org/10.1247/csf.20.415
https://www.ncbi.nlm.nih.gov/pubmed/8825061
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:A1995TT69500001&DestApp=WOS_CPL