AJP - Lung Cellular and Molecular Physiology, Vol 268, Issue 2 162-L165, Copyright © 1995 by American Physiological Society
Human SP-A: then and now
J. Floros and A. M. Karinch
Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey 17033.
In the short span of ten years, our understanding of human
surfactant-associated protein A (SP-A) has advanced rapidly at both the
level of the protein and the level of the gene. In the period 1984-1988,
the protein was biochemically characterized and two SP-A precursors were
identified. The molecular characterization was begun with the publication
of an SP-A genomic sequence and sequences of two SP-A cDNAs, suggesting the
presence of two SP-A genes. In the period 1991-1992, an SP-A pseudogene, a
second SP-A genomic sequence, and an SP-A allelic variant were described.
Since that time, a picture of increasing complexity has emerged from
studies of the two SP-A genes. This complexity includes alternative
splicing of 5' untranslated exons, allelic variants of both SP-A genes, and
sequence heterogeneity within the 3' untranslated region. The challenge for
the future will be to discover the physiological significance of the
genetic complexity of human SP-A.
