Structure
The encoded protein has a 47 amino acid signal peptide, an extracellular domain of 1930 residues, a 25 residue transmembrane domain and a 43 amino acid C terminal cytoplasmic region. The leader sequence and 5'-untranslated region are contained in one exon. The large extracellular domain of CR1, which has 25 potential N-glycosylation sites, can be divided into 30 short consensus repeats (SCRs) (also known as complement control protein repeats (CCPs) or sushi domains), each having 60 to 70 amino acids. The sequence homology between SCRs ranges between 60 to 99 percent. The transmembrane region is encoded by 2 exons and the cytoplasmic domain and the 3'-untranslated regions are coded for by two separate exons.
The 30 or so SCRs are further grouped into four longer regions termed long homologous repeats (LHRs) each encoding approximately 45 kDa of protein and designated LHR-A, -B, -C, and -D. The first three have seven SCRs while LHR-D has 9 or more. Each LHR is composed of 8 exons and within an LHR, SCR 1, 5, and 7 are each encoded by a single exon, SCR 2 and 6 are each encoded by 2 exons, and a single exon codes for SCR 3 and 4. The LHR seem to have arisen as a result of unequal crossing over and the event that gave rise to LHR-B seems to have occurred within the fourth exon of either LHR-A or –C. To date the atomic structure have been solved for SCRs 15-16, 16 & 16-17.
Read more about this topic: Complement Receptor 1
Famous quotes containing the word structure:
“When a house is tottering to its fall,
The strain lies heaviest on the weakest part,
One tiny crack throughout the structure spreads,
And its own weight soon brings it toppling down.”
—Ovid (Publius Ovidius Naso)
“... the structure of our public morality crashed to earth. Above its grave a tombstone read, “Be tolerant—even of evil.” Logically the next step would be to say to our commonwealth’s criminals, “I disagree that it’s all right to rob and murder, but naturally I respect your opinion.” Tolerance is only complacence when it makes no distinction between right and wrong.”
—Sarah Patton Boyle, U.S. civil rights activist and author. The Desegregated Heart, part 2, ch. 2 (1962)
“For the structure that we raise,
Time is with materials filled;
Our to-days and yesterdays
Are the blocks with which we build.”
—Henry Wadsworth Longfellow (1809–1882)