Question

Using the amino acid sequence of the protein you identified in question 1D, answer the following questions relating to humans.

The sequence is

MLSFVDTRTLLLLAVTSCLATCQCKCLQLVSGSLGKSGDRGPRGERGPPGPPGRDGDDGIPGPPGPPGPPGPPGLGGNFA AQFDAKGGGPGPMGLMGPRGPPGASGAPGPQGFQGPPGEPGEPGQTGPAGARGPPGPPGKAGEDGHPGKPGRPGERGVVG PQGARGFPGTPGLPGFKGIRGHNGLDGLKGQPGAPGVKGEPGAPGENGTPGQTGARGLPGERGRVGAPGPAGARGSDGSV GPVGPAGPIGSAGPPGFPGAPGPKGELGPVGNPGPAGPAGPRGEVGLPGLSGPVGPPGNPGANGLPGAKGAAGLPGVAGA PGLPGPRGIPGPVGASGATGARGLVGEPGPAGSKGESGNKGEPGAVGQPGPPGPSGEEGKRGSTGEIGPAGPPGPPGLRG NPGSRGLPGADGRAGVMGPAGSRGATGPAGVRGPNGDSGRPGEPGLMGPRGFPGSPGNIGPAGKEGPVGLPGIDGRPGPI GPAGARGEPGNIGFPGPKGPSGDPGKAGEKGHAGLAGARGAPGPDGNNGAQGPPGLQGVQGGKGEQGPAGPPGFQGLPGP AGTAGEAGKPGERGIPGEFGLPGPAGARGERGPPGESGAAGPTGPIGSRGPSGPPGPDGNKGEPGVVGAPGTAGPSGPSG LPGERGAAGIPGGKGEKGETGLRGDIGSPGRDGARGAPGAIGAPGPAGANGDRGEAGPAGPAGPAGPRGSPGERGEVGPA GPNGFAGPAGAAGQPGAKGERGTKGPKGENGPVGPTGPVGAAGPSGPNGPPGPAGSRGDGGPPGATGFPGAAGRTGPPGP SGISGPPGPPGPAGKEGLRGPRGDQGPVGRSGETGASGPPGFVGEKGPSGEPGTAGPPGTPGPQGLLGAPGFLGLPGSRG ERGLPGVAGSVGEPGPLGIAGPPGARGPPGNVGNPGVNGAPGEAGRDGNPGNDGPPGRDGQPGHKGERGYPGNAGPVGAA GAPGPQGPVGPVGKHGNRGEPGPAGAVGPAGAVGPRGPSGPQGIRGDKGEPGDKGPRGLPGLKGHNGLQGLPGLAGHHGD QGAPGAVGPAGPRGPAGPSGPAGKDGRIGQPGAVGPAGIRGSQGSQGPAGPPGPPGPPGPPGPSGGGYEFGFDGDFYRAD QPRSPTSLRPKDYEVDATLKSLNNQIETLLTPEGSRKNPARTCRDLRLSHPEWSSGYYWIDPNQGCTMDAIKVYCDFSTG ETCIRAQPEDIPVKNWYRNSKAKKHVWVGETINGGTQFEYNVEGVTTKEMATQLAFMRLLANHASQNITYHCKNSIAYMD EETGNLKKAVILQGSNDVELVAEGNSRFTYTVLVDGCSKKTNEWQKTIIEYKTNKPSRLPILDIAPLDIGGADQEIRLNI GPVCFK

A) What is the human homolog of the protein?

B) What is the predicted localization of the protein?

C) Where WITHIN a cell is the protein predominantly found?

Answer 1

According to NCBI Protein BLAST, the given amino acid sequence showed 100% identity to collagen alpha-2(I) chain [Bos mutus].

To find out the human homolog of the protein, following steps were taken

1. Copy and paste the given sequence on NCBI PROTEIN BLAST.

2. In the organism blank, put humans or homo sapiens.

3. Click on blast.

The human homolog of the protein was found out to be collagen, type I, alpha 2[Homo sapiens] with 92.32% identity.

The predicted localization of the protein in humans is connective tissues namely skin, tendon, bone. Accounting for more than 90% of the organic mass of the bone and being the major component of skin, ligaments and tendon.

The gene encoding this protein is present on chromosome 7.

It is synthesized as a procollagen precursor molecule which is then cotranslationally translocated into the lumen of rough endoplasmic reticulum. Hence within a cell the protein is predominantly found in the lumen of rough endoplasmic reticulum.

After post translational modification proper folding of the polypeptide takes place in the endoplasmic reticulum. Later the procollagen molecules are transported through the golgi complex and released out of the cell. Wherein the mature collagen molecules arrange themselves into long, thin fibrils which cross-link in the spaces between the cells forming a mesh like network of the collagen fibres.