<SEC-DOCUMENT>0001567619-21-005077.txt : 20210226
<SEC-HEADER>0001567619-21-005077.hdr.sgml : 20210226
<ACCEPTANCE-DATETIME>20210226170817
ACCESSION NUMBER:		0001567619-21-005077
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210225
FILED AS OF DATE:		20210226
DATE AS OF CHANGE:		20210226

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Zago Wagner M.
		CENTRAL INDEX KEY:			0001708681

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-35676
		FILM NUMBER:		21690870

	MAIL ADDRESS:	
		STREET 1:		C/O PROTHENA BIOSCIENCES INC
		STREET 2:		331 OYSTER POINT BOULEVARD
		CITY:			SOUTH SAN FRANCISCO
		STATE:			CA
		ZIP:			94080

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PROTHENA CORP PUBLIC LTD CO
		CENTRAL INDEX KEY:			0001559053
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			L2
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		77 SIR JOHN ROGERSON'S QUAY, BLOCK C
		STREET 2:		GRAND CANAL DOCKLANDS
		CITY:			DUBLIN 2
		STATE:			L2
		ZIP:			D02 T804
		BUSINESS PHONE:		011-353-1-236-2500

	MAIL ADDRESS:	
		STREET 1:		77 SIR JOHN ROGERSON'S QUAY, BLOCK C
		STREET 2:		GRAND CANAL DOCKLANDS
		CITY:			DUBLIN 2
		STATE:			L2
		ZIP:			D02 T804

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Prothena Corp plc
		DATE OF NAME CHANGE:	20121102

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Neotope Corp Ltd
		DATE OF NAME CHANGE:	20120926
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-02-25</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001559053</issuerCik>
        <issuerName>PROTHENA CORP PUBLIC LTD CO</issuerName>
        <issuerTradingSymbol>PRTA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001708681</rptOwnerCik>
            <rptOwnerName>Zago Wagner M.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O PROTHENA BIOSCIENCES INC</rptOwnerStreet1>
            <rptOwnerStreet2>331 OYSTER POINT BOULEVARD</rptOwnerStreet2>
            <rptOwnerCity>SOUTH SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94080</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Scientific Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>22.60</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2021-02-25</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>56000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2031-02-25</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>56000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>56000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The shares subject to the option will vest and become exercisable as to 25% of the total number of shares subject to the option on February 25, 2022 and with respect to 1/48th of the total number of shares subject to the option in successive, equal monthly installments on each monthly anniversary thereafter, subject to the Reporting Person's continued employment with the Issuer on each such vesting date.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Michael Malecek, as Attorney in Fact for Wagner M. Zago</signatureName>
        <signatureDate>2021-02-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
