Cloning and characterization of two cDNAs coding for human von Willebrand factor

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• Von Willebrand factor (vWF) is crucial for hemostasis, mediating platelet adhesion and stabilizing factor VIII.
• Understanding vWF's genetic and protein structure is essential for diagnosing and treating bleeding disorders.

Purpose of the Study:

• To isolate and characterize cDNA clones encoding human von Willebrand factor.
• To determine the sequence and structural features of vWF from endothelial cells.
• To analyze the proteolytic processing and evolutionary origins of vWF.

Main Methods:

• Construction of a lambda gt11 bacteriophage cDNA library from human umbilical vein endothelial cell poly(A)+ RNA.
• Screening of 2.5 million recombinants using antibodies against human vWF.
• DNA sequencing of cDNA inserts and comparison with protein sequence data (Edman degradation).

Main Results:

• Two cDNA clones, lambda HvWF1 and lambda HvWF3, were identified, coding for vWF.
• The clones collectively represent over 80% of the mature vWF sequence, including leader sequences and 3' noncoding regions.
• Analysis revealed proteolytic processing occurs at the amino-terminal end and identified repetitive sequences and an Arg-Gly-Asp-Ser motif.

Conclusions:

• The isolated cDNA clones provide a significant portion of the human vWF sequence.
• The findings elucidate vWF biosynthesis, processing, and structural organization, including evidence of gene duplication.
• The presence of the RGD sequence suggests a role in cell adhesion and platelet binding.