Surfactant protein A is localized at the corners of the pulmonary tubular myelin lattice.
Immunogold labeling on sections of a freeze-substituted tubular myelin-enriched fraction isolated from a bronchoalveolar lavage of rat lung showed that surfactant protein A (SP-A) occurs predominantly at the corners of the tubular myelin lattice. Seventy-nine percent of the gold particles were located within 20 nm from a corner. Extracellular SP-A was detected only in the tubular myelin lattice and not in vesicles or secreted lamellar bodies. Ultra-thin cryosections of rat lung fixed in vivo showed that intracellular SP-A was distributed homogeneously over the stacked membranes of lamellar bodies in alveolar Type II cells. The presence of SP-A at the corners of the tubular myelin lattice suggests an important role of this protein in the formation and/or maintenance of this highly ordered lattice.
Department of Cell Biology, Medical School, University of Utrecht, The Netherlands.
W F
WF
Voorhout
T
T
Veenendaal
H P
HP
Haagsman
A J
AJ
Verkleij
L M
LM
van Golde
H J
HJ
Geuze
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D005109:Extracellular Matrix / Q000737:chemistry / Q000648:ultrastructure; D006046:Gold; D007150:Immunohistochemistry / Q000379:methods; D008168:Lung / Q000737:chemistry* / Q000166:cytology / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D009186:Myelin Sheath / Q000737:chemistry*; D011510:Proteolipids / Q000032:analysis*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000032:analysis*; D051381:Rats
D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D006046:Gold