Intracellular pathways of protein synthesis and secretion in the hepatocyte.
The multiplicity of data summarized in this review indicate a variety of signals built into the intrinsic structure of secretory, membrane-associated, and lysosomal glycoproteins, which direct these complex molecules toward specific cellular organelles. Some of these signals (such as the NH2-terminal signal segment) are discarded when the appropriate transfer has been completed. Others are retained as a permanent intrinsic component of the molecule. Although evidence has been presented that the carbohydrate moieties of glycoproteins are not essential for secretion, they probably subserve a role in the interaction of glycoproteins with membrane receptors on intracellular organelles. Undoubtedly, other examples of permanent molecular signals will be described in the future, which will provide a comprehensive picture of the integrated transport activity of the membrane channels of the secretory pathway of the hepatocyte.
D000818:Animals; D003599:Cytoskeleton / Q000502:physiology; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006023:Glycoproteins / Q000096:biosynthesis* / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D009844:Oligosaccharides / Q000378:metabolism
D006023:Glycoproteins; D009844:Oligosaccharides