The transmembrane domain of surfactant protein C precursor determines the morphology of the induced membrane compartment in CHO cells.
Surfactant protein C (SP-C) is a small lipopeptide of which the main part consists of a typical valyl-rich transmembrane domain. The protein is expressed as a propeptide (proSP-C) which is processed and sorted via the regulated secretory pathway to the lamellar body, where mature SP-C is stored before secretion into the alveolar space. In this study we investigated the identity of the compartment to which proSP-C is sorted in cells that do not have a regulated secretory pathway, such as CHO cells. By electron microscopy we determined that proSP-C was localized in an uncommon membrane compartment with very regular morphology, which was not present in control cells. This membrane compartment is not influenced by the palmitoylation of proSP-C and is probably derived from the endoplasmic reticulum. However, proSP-C chimeras with artificial transmembrane domains induced a membrane compartment with a different morphology. Therefore we propose that the typical amino acid sequence of the transmembrane domain of proSP-C plays a role in membrane formation and morphology, which may be relevant under physiological conditions.
ten Brinke
Anja
A
Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Institute of Biomembranes, Utrecht University, Utrecht, The Netherlands.
Posthuma
George
G
Batenburg
Joseph J
JJ
Haagsman
Henk P
HP
Ridder
Anja N J A
AN
van Golde
Lambert M G
LM
Vaandrager
Arie B
AB
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D006224:Cricetinae; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D007425:Intracellular Membranes / Q000378:metabolism* / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D010455:Peptides / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011499:Protein Processing, Post-Translational; D037721:Pulmonary Surfactant-Associated Protein C / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011663:Pulmonary Surfactants / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D003470:Culture Media; D010455:Peptides; D037721:Pulmonary Surfactant-Associated Protein C; D011663:Pulmonary Surfactants