The following text describes a protein:
Function:
[Reticulocyte-binding protein homolog 1 240 kDa form]: During the asexual blood stage, binds to a sialic acid containing receptor on the surface of the host erythrocyte and thus is involved in merozoite invasion. Binds erythrocytes via a neuraminidase sensitive and trypsin-, chymotrypsin-resistant receptor. After merozoite attachment and reorientation, RH1 binding to its erythrocyte receptor triggers an increase in intracellular Ca(2+) within the parasite resulting in the release of microneme proteins such as EBA175 which in turn leads to the formation of the tight junction between parasite and host cell.
Miscellaneous:
MISCELLANEOUS: RH1 expression levels greatly vary between isolates in part due to multiple RH1 gene copies; levels are high in isolates W2mef, FCR3, FCB1 and T994, and low in isolates 3D7, HB3, K1, 7G8, T996 and Dd2. A similar variation in expression affects other reticulocyte-binding proteins such as RH2a and RH2b. The expression pattern of RH1 and RH2 allows the strain to use different invasion pathways to enter erythrocytes (Probable). This provides a mechanism of phenotypic variation to evade host immune responses and to adapt to the polymorphic nature of the erythrocyte receptors in human populations (Probable).
Subcellular Localization:
[Reticulocyte-binding protein homolog 1]: Cell membrane; Single-pass type I membrane protein. Note=Localizes to apical organelles in the maturing schizont and then translocates to the apical surface of the merozoite; [Reticulocyte-binding protein homolog 1 240 kDa form]: Secreted. Cell junction, tight junction. Cytoplasmic vesicle, secretory vesicle, rhoptry. Note=Localized to the rhoptry neck at the apical end of the merozoite. During merozoite invasion, mainly localizes to the tight junction formed between the parasite and the host erythrocytes membranes and then moves with the tight junction to the posterior end as the parasite enters the erythrocyte. The remaining protein that does not participate in the tight junction, remains at the apical end of the merozoite and is incorporated into the newly formed ring stage; [Reticulocyte-binding protein homolog 1 120 kDa form]: Cell membrane; Single-pass type I membrane protein. Cell junction, tight junction. Cytoplasmic vesicle, secretory vesicle, rhoptry. Note=Localized to the rhoptry neck at the apical end of the merozoite. During merozoite invasion, mainly localizes to the tight junction formed between the parasite and the host erythrocytes membranes and then moves with the tight junction to the posterior end as the parasite enters the erythrocyte. The remaining protein that does not participate in the tight junction, remains at the apical end of the merozoite and is incorporated into the newly formed ring stage.
Sequence:
MQRWIFCNIVLHILIYLAEFSHEQESYSSNEKIRKDYSDDNNYEPTPSYEKRKKEYGKDESYIKNYRGNNFSYDLSKNSSIFLHMGNGSNSKTLKRCNKKKNIKTNFLRPIEEEKTVLNNYVYKGVNFLDTIKRNDSSYKFDVYKDTSFLKNREYKELITMQYDYAYLEATKEVLYLIPKDKDYHKFYKNELEKILFNLKDSLKLLREGYIQSKLEMIRIHSDIDILNEFHQGNIINDNYFNNEIKKKKEDMEKYIREYNLYIYKYENQLKIKIQKLTNEVSINLNKSTCEKNCYNYILKLEKYKNIIKDKINKWKDLPEIYIDDKSFSYTFLKDVINNKIDIYKTISSFISTQKQLYYFEYIYIMNKNTLNLLSYNIQKTDINSSSKYTYTKSHFLKDNHILLSKYYTAKFIDILNKTYYYNLYKNKILLFNKYIIKLRNDLKEYAFKSIQFIQDKIKKHKDELSIENILQEVNNIYIKYDTSINEISKYNNLIINTDLQIVQQKLLEIKQKKNDITHKVQLINHIYKNIHDEILNKKNNEITKIIINNIKDHKKDLQDLLLFIQQIKQYNILTDHKITQCNNYYKEIIKMKEDINHIHIYIQPILNNLHTLKQVQNNKIKYEEHIKQILQKIYDKKESLKKIILLKDEAQLDITLLDDLIQKQTKKQTQTQTQTQKQTLIQNNETIQLISGQEDKHESNPFNHIQTYIQQKDTQNKNIQNLLKSLYNGNINTFIDTISKYILKQKDIELTQHVYTDEKINDYLEEIKNEQNKIDKTIDDIKIQETLKQITHIVNNIKTIKKDLLKEFIQHLIKYMNERYQNMQQGYNNLTNYINQYEEENNNMKQYITTIRNIQKIYYDNIYAKEKEIRSGQYYKDFITSRKNIYNIRENISKNVDMIKNEEKKKIQNCVDKYNSIKQYVKMLKNGDTQDENNNNNNDIYDKLIVPLDSIKQNIDKYNTEHNFITFTNKINTHNKKNQEMMEEFIYAYKRLKILKILNISLKACEKNNKSINTLNDKTQELKKIVTHEIDLLQKDILTSQISNKNVLLLNDLLKEIEQYIIDVHKLKKKSNDLFTYYEQSKNYFYFKNKKDNFDIQKTINKMNEWLAIKNYINEINKNYQTLYEKKINVLLHNSKSYVQYFYDHIINLILQKKNYLENTLKTKIQDNEHSLYALQQNEEYQKVKNEKDQNEIKKIKQLIEKNKNDILTYENNIEQIEQKNIELKTNAQNKDDQIVNTLNEVKKKIIYTYEKVDNQISNVLKNYEEGKVEYDKNVVQNVNDADDTNDIDEINDIDEINDIDEINDIDEINDIDEIKDIDHIKHFDDTKHFDDIYHADDTRDEYHIALSNYIKTELRNINLQEIKNNIIKIFKEFKSAHKEIKKESEQINKEFTKMDVVINQLRDIDRQMLDLYKELDEKYSEFNKTKIEEINNIRENINNVEIWYEKNIIEYFLRHMNDQKDKAAKYMENIDTYKNNIEIISKQINPENYVETLNKSNMYSYVEKANDLFYKQINNIIINSNQLKNEAFTIDELQNIQKNRKNLLTKKQQIIQYTNEIENIFNEIKNINNILVLTNYKSILQDISQNINHVSIYTEQLHNLYIKLEEEKEQMKTLYHKSNVLHNQINFNEDAFINNLLINIEKIKNDITHIKEKTNIYMIDVNKSKNNAQLYFHNTLRGNEKIEYLKNLKNSTNQQITLQELKQVQENVEKVKDIYNQTIKYEEEIKKNYHIITDYENKINDILHNSFIKQINMESSNNKKQTKQIIDIINDKTFEEHIKTSKTKINMLKEQSQMKHIDKTLLNEQALKLFVDINSTNNNLDNMLSEINSIQNNIHTYIQEANKSFDKFKIICDQNVNDLLNKLSLGDLNYMNHLKNLQNEIRNMNLEKNFMLDKSKKIDEEEKKLDILKVNISNINNSLDKLKKYYEEALFQKVKEKAEIQKENIEKIKQEINTLSDVFKKPFFFIQLNTDSSQHEKDINNNVETYKNNIDEIYNVFIQSYNLIQKYSSEIFSSTLNYIQTKEIKEKSIKEQNQLNQNEKEASVLLKNIKINETIKLFKQIKNERQNDVHNIKEDYNLLQQYLNYMKNEMEQLKKYKNDVHMDKNYVENNNGEKEKLLKETISSYYDKINNINNKLYIYKNKEDTYFNNMIKVSEILNIIIKKKQQNEQRIVINAEYDSSLINKDEEIKKEINNQIIELNKHNENISNIFKDIQNIKKQSQDIITNMNDMYKSTILLVDIIQKKEEALNKQKNILRNIDNILNKKENIIDKVIKCNCDDYKDILIQNETEYQKLQNINHTYEEKKKSIDILKIKNIKQKNIQEYKNKLEQMNTIINQSIEQHVFINADILQNEKIKLEEIIKNLDILDEQIMTYHNSIDELYKLGIQCDNHLITTISVVVNKNTTKIMIHIKKQKEDIQKINNYIQTNYNIINEEALQFHRLYGHNLISEDDKNNLVHIIKEQKNIYTQKEIDISKIIKHVKKGLYSLNEHDMNHDTHMNIINEHINNNILQPYTQLINMIKDIDNVFIKIQNNKFEQIQKYIEIIKSLEQLNKNINTDNLNKLKDTQNKLINIETEMKHKQKQLINKMNDIEKDNITDQYMHDVQQNIFEPITLKMNEYNTLLNDNHNNNINNEHQFNHLNSLHTKIFSHNYNKEQQQEYITNIMQRIDVFINDLDTYQYEYYFYEWNQEYKQIDKNKINQHINNIKNNLIHVKKQFEHTLENIKNNENIFDNIQLKKKDIDDIIININNTKETYLKELNKKKMLQNKKKVDEKSEINNHHTLQHDNQNVEQKNKIKDHNLITKPNNNSSEESHQNEQMKEQNKNILEKQTRNIKPHHVHNHNHNHNQNQKDSTKLQEQDISTHKLHNTIHEQQSKDNHQGNREKKQKNGNHERMYFASGIVVSILFLSSLGFVINSKNNKQEYDKEQEKQQQNDFVCDNNKMDDKSTQKYGRNQEEVMEISFDNDYI